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Hi, and welcome to the Neil
Ashton Podcast.

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In each episode, we explained
some of the fascinating ways

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that science and engineering are
changing the world around us.

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We talked to leading engineers
from elite level sports like

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cycling in Formula One to some
of the world's top academics to

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understand how fluid dynamics,
machine learning, supercomputing

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are bringing in a new era
discovery.

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We also hear some of their life
stories, their career advice,

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the lessons they've learned on
the way that I hope will be

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helpful to you too.
So sit back and enjoy this

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episode.
Hi, and welcome back to the Neil

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Ashton Podcast.
I just finished recording

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today's episode with Professor
Brian Launder, the incredible

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person who has truly been one of
The Pioneers and legends of

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computational fluid dynamics and
fluid dynamics more broadly.

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He is most well known for the
Kepps Island model, for the LLR

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mental stress model.
And I would argue, and I didn't

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fully appreciate it until after
actually speaking to him, just

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the number of people that he
supervised, mentored and

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brought, you know, these people
like Bill Jones and Kimo and

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Mike Leschina and Tim Kraft and
Hector Acuvides, who are people

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that themselves have gone on to
supervise people.

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You know, this is the thing with
academia.

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One of the core roles I believe
of of as a professor is

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research, of course, but the
people that they nurture and

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then bring on to go into
industry, go into academia is

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the real credit.
And so many people have

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benefited from from what he's
done.

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It's hard to believe that most
of this stuff was done in the

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1970s, fifty years ago.
Today we are still using the K

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epsilon model.
If you're doing ACFD simulation

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of many different objects,
whether you know heat transfer

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cars, engines, you're probably
using what the Kepson or some

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variant of it or, or Reynolds
stress model.

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And the fact that that was done
in the 70s when computers, you

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know, he was telling us that you
have to walk up to the building.

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There was no SSH remote access
punch cards, you know, the codes

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were just being written.
It was incredible.

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I genuinely in awe of the
development that happened back

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then and it we we went through
essentially his life story from

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his undergraduate years moving
across to the US from Imperial

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to then MIT coming back to
Imperial, the role of Brian

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Spaulding, a key interesting one
that we reflect on at the

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beginning and the end, you know,
incredible at that time, the

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turbulent time of how the Champ
Code came about and some of the

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tensions around that.
His ultimate move to you missed

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now the University of
Manchester.

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And as I said, the the key
developments around the Eddie

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viscosity model, second moment
closure models, but also things

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like the wall functions that I
mentioned to him is now even

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more relevant in the context of
Walmart, LS etcetera.

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And just yeah, an incredible
person.

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And I think some of the advice
and lessons you get from it, it

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reminds you even the greatest
people have some of the

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challenges that that we have.
And, and they don't realize at

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the time the amazing work that
they're doing.

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But yeah, really, really special
person.

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And someone I really liked
speaking to, you know, he's a

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fellow with the Royal Society.
He's he's done so many things.

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He's you know, how many good
citations, you know, 10s of

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thousands, super high hate
index, all of all of the things,

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of course, that a top professor
would have.

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So if you're looking for the
pinnacle of people in the

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simulation world, quite a few of
his people he supervised and

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worked with have now gone off
into some of these major

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multibillion dollar companies.
In fact, if you use these big

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simulation codes, many of them
are the foundations are on the

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work that the professor Brian
Launder was part of or, or or

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leading.
And so, yeah, really interesting

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story as as we've ever.
There was lots of things that I

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could have asked him.
We did talk a little bit about

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some of the rivalry with
Spallard and and mentor and

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Wilcox and of course, you know,
Professor Launder's gentleman.

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And then I genuinely think his
focus was more on the research.

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But it's always interesting to
us who used turbans models to

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understand, you know, what was
the difference between these

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these key figures, I guess at
the time.

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But so I hope you enjoy this
episode.

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I genuinely really did.
I, I mentioned that I studied

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the University of Manchester.
I was taught by Professor

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Laundus.
So it was one of my good

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friends, Alistair W, who was
also his last PhD student.

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And yeah, it's it was an honor
to speak to him.

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And I hope you enjoyed this as
much as I did speaking to him.

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So sit back and enjoy this
episode with Professor Brian

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Lauder.
Thank you very much for agreeing

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to do this.
I really appreciate you taking

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the time to speak to me today.
And I thought maybe it would be

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good for the people listening
to, you know, hear about your

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early days, where it all began
and you starting off, you know,

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what did you do at university?
What was your undergraduate

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studies?
OK, well that doesn't sound a

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bad place to start.
Let's let's begin with early

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1961.
I was in the final year of my

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bachelor's program at Imperial
College.

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I found a topic that really
interested me, convective heat

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transfer, and I was doing a
final year project on flows

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related to boiling.
When I heard that the new

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professor of heat transfer was
going to talk about postgraduate

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opportunities, I was quite
excited.

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I made sure to attend because I
knew by then that I would like

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to do postgraduate work.
So I went along to the meeting

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that he was to address, and he
probably did talk about the

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range of opportunities that
there might be.

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But what I remembered were a
particular sentence or two that

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he presented us with.
He said, you well know that the

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college is being rebuilt, and
they're rebuilding it on the

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same site as the present
building.

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This will inevitably mean
interruptions and delays.

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So if you're looking for a fast
PhD, you ought to go elsewhere.

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This was a very deflating
statement from him.

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A day or two later, I asked my
closest friend in the course guy

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called Hugh Kendrick what he
planned to do.

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He chuckled, looked at me and
said I'll probably go to

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America.
I fancy doing a master's program

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at Yale or Princeton.
Which time I interrupted him and

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said, you're talking rubbish.
What would a top American

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University do having a thick O
like Q?

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We both chuckled at that point
and moved on to other things.

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But you know, when I was alone
reflecting on this in the

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evening, I thought that's,
that's a pretty neat idea.

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So I wrote to a half dozen
universities in the USA seeking

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graduate or postgraduate
engagement there, together with

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funding.
Nothing happened for several

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weeks, of course, but then
responses started to come in and

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I was absolutely delighted.
Princeton offered me a name

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scholarship that would cover my
tuition fees, my living costs to

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do research on whatever I wanted
to do.

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There was a second offer from
MIT that was specifically to

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work in boiling heat transfer,
which was a subject that I I was

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really interested in.
However, the downsize was that I

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had to earn my keep as a
teaching assistant, that I'd

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spend maybe 1520 even 20 hours a
week tutoring students probably

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brighter than me on on the
various courses they'd be

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taking.
So I knew where my preference

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was, but I thought I'd go back
and ask her for an appointment

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with Brian Spaulding to confirm
my choice.

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His secretary graciously gave me
a 5 minute interview slot.

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I went in and took perhaps a
minute describing my fortunate

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pair of choices and he said
Princeton.

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Huh.
Well, Princeton's Princeton.

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Scott Drake, who's just
co-authored a heat transfer

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textbook with Professor Eckert.
But you know, from my meetings

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with him, Drake hasn't had an
original idea in his life.

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Go to MIT with Rose now and do
boiling heat transfer.

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This response somewhat deflated
me again, but equally I felt I

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had to take take his advice and
reluctantly declined the

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Princeton scholarship.
But before I got to write to

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MIT, a counter offer came in
from their gas turbine

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laboratory and the important
difference was that they offered

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me not a teaching assistantship,
but a research assistantship.

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This meant that I would do
research on one of their

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projects, which would also
become my thesis.

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This was a no brainer for me at
any rate.

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So I accepted that offer.
I declined the heat transfer

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offer, and I'm afraid that from
there on in my life, boiling

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heat transfer had sunk beneath
my horizon.

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OK, Well, before I talk about my
research at MIT and thereafter,

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let me just switch back for a
minute to Hugh Kendrick.

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We were talking one day and I
said to him, hey, I have

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accepted a postgraduate position
at MIT, where are you going?

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You'd talked about going to
Princeton or Yale.

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I suddenly realized I was
talking that someone with the

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blood draining from his face.
He was literally dumbfounded at

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what I told him.
Eventually he muttered that he

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had a he had a graduate
apprenticeship, signed up with

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Vickers, that he hadn't even
been looking at other

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opportunities.
He'd go and complete his

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postgraduate apprenticeship with
them.

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But then I could almost see the
wheels turning around in his

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brain.
He said with you could see

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growing confidence, he said, But
I was under 21 when I signed

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that contract.
It's not enforceable.

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And I'm sure MIT will take in a
thick O like you, They'll,

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they'll find a place for me.
Well, he was right.

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They did find a place for him,
but by then it was two or three

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months after I'd been in touch
with them.

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They'd allocated all their
funding for the year.

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However, not to be deterred, he
applied to Caltech on the other

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side of America and was offered
a teaching assistantship.

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And that was in August 1961.
He and I sailed across in a very

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tiny cabin on the Queen Mary
together.

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Thereafter I caught the train up
to MIT, or rather to Boston.

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But then Boston is just across
the Charles River in Cambridge

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and not a just a short distance.
He flew out to Los Angeles and

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indeed made the rest of his life
in America that.

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That's that's amazing.
And I I'm more interested and I

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don't know if other people
hearing this is the comment

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about sailing across from the
Queen Mary, mainly because now

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if I go to America and it'll
probably the same for you, you

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know, it's a flight.
How long did it take on the

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boat?
It was it was a five day flight.

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It was convenient because we
worked on 25 hour days so that

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so that we are on the right
time.

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When we finally arrived in New
York, it was fine, fine sea

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journeys, a bit boring, you
know, try to amuse oneself.

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We had a tiny cabin, but we
would sneak through into the,

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I'm not sure if it was first
class or second class areas and

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were able to watch films and and
and so on in their luxury,

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luxury cinemas.
And so that they had on.

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It was an interesting experience
to do once.

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The other thing I remember was
that as we got close to New

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York, you close to?
Yeah, the final destination, the

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air became more and more humid.
So now I remember a site sailing

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past the Statue of Liberty.
Of course.

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But it was absolutely 9090%
humidity by then it it was

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difficult.
Anyway, that must have been a

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moment, though, to see the
Statue of Liberty coming to

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America with your friend.
Yeah, that's a that's a great

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point.
So what happened then when you

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got to to MIT?
How did you decide what research

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projects to welcome?
Well, I was simply checked in

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there and they gave me a folder
with perhaps 15 research

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projects summarized in there,
the sufficient amount of

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background that one could make a
decision, and I knew pretty much

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straight away what my choice
would be.

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At Imperial I'd learned the
rudiments of boundary layer

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transition.
That is to say, a boundary layer

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developed initially was laminar,
but then when the Reynolds

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number got high enough,
conditions were right for a

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transition to a turbulent
boundary layer and there and

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turbulent it remained.
But this this outline

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description that I was reading
said that couple of Soviet

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scientists had found that in
supersonic flow, if a turbulent

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boundary layer was passed around
what is called a a prantlemyer

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expansion, essentially that's a
series of waves that one might

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00:14:39,360 --> 00:14:43,040
go through in turning a corner
and the flow is through that

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00:14:43,040 --> 00:14:48,120
expansion greatly accelerated.
They found that downstream they

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00:14:48,120 --> 00:14:50,560
had a laminar boundary layer
growing again.

230
00:14:51,120 --> 00:14:58,000
So this project outlines said
you will determine whether in

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00:14:58,240 --> 00:15:03,240
subsonic flow a boundary layer
that's strongly accelerated also

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00:15:03,520 --> 00:15:08,920
can revert back to turbulent.
So sorry to Lamina and I knew I

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00:15:08,920 --> 00:15:12,800
had to take that it, it just
seemed very a very interesting

234
00:15:12,800 --> 00:15:17,120
topic and it occupied the next
three years of my life doing

235
00:15:17,160 --> 00:15:21,680
doing research there.
And the outcome was that yes,

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00:15:21,960 --> 00:15:25,160
you could make a turbulent
boundary layer go back to

237
00:15:25,160 --> 00:15:27,560
laminar or at least towards
laminar.

238
00:15:27,640 --> 00:15:32,000
I established the acceleration
parameter, dimensionless

239
00:15:32,000 --> 00:15:36,200
acceleration parameter that
would determine when that would

240
00:15:36,200 --> 00:15:41,760
take place and how roughly how
big the parameter was.

241
00:15:41,840 --> 00:15:46,840
I even developed what would be
called a simple integral profile

242
00:15:46,840 --> 00:15:50,200
method of predicting the
phenomenon based on the idea

243
00:15:50,200 --> 00:15:54,680
that whilst the viscous stresses
were greatly increased by the

244
00:15:54,960 --> 00:15:58,760
acceleration, that happened too
quickly for the turbulent

245
00:15:58,760 --> 00:16:01,680
stresses to respond.
So I just left those as they

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00:16:01,720 --> 00:16:06,240
were and doing calculations
based on that idea pretty much

247
00:16:06,320 --> 00:16:10,360
imitate mimic the experiments
that I'd.

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00:16:10,480 --> 00:16:15,600
OK, so now having finished my
work at MIT, what next?

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00:16:15,600 --> 00:16:20,760
There were there were jobs
available for PhD graduates from

250
00:16:20,760 --> 00:16:26,200
MIT offering $14,000 or so a
year, but I wasn't eligible to

251
00:16:26,200 --> 00:16:32,280
apply for those.
I'd taken a a Fulbright travel

252
00:16:32,280 --> 00:16:36,880
grant to come across to the US,
but remember that at the end of

253
00:16:36,880 --> 00:16:40,880
it, I had to go back.
So finding a job back in

254
00:16:40,880 --> 00:16:46,560
England, I'd had one or two
offers came in for postgraduate

255
00:16:46,720 --> 00:16:50,960
research studentships.
Not studentships, postgraduate

256
00:16:51,920 --> 00:16:57,080
employment at government
laboratories like the National

257
00:16:57,080 --> 00:17:00,800
Gas Turbine Establishment,
central electricity research

258
00:17:00,800 --> 00:17:02,920
labs, and so on.
They were.

259
00:17:03,560 --> 00:17:07,079
They weren't uninteresting, but
they didn't quite tick all the

260
00:17:07,079 --> 00:17:10,240
boxes.
So I decided to write to Brian

261
00:17:10,240 --> 00:17:15,760
Spalding again and wondering
whether there was a post and he

262
00:17:15,760 --> 00:17:20,680
said send ACV.
So I send ACV of what I'd

263
00:17:20,920 --> 00:17:25,440
accomplished and I just was
working on proofs of the 1st

264
00:17:25,440 --> 00:17:29,800
paper that I'd written and I
decided to send those along too

265
00:17:29,800 --> 00:17:32,400
for good measure.
It may sound a long time.

266
00:17:32,400 --> 00:17:35,440
Everything was roughly 2 weeks
between writing and getting.

267
00:17:35,440 --> 00:17:36,600
I was just.
Going to say yeah.

268
00:17:37,240 --> 00:17:38,160
It wasn't.
E-mail.

269
00:17:38,720 --> 00:17:41,080
Yeah, yeah, there wasn't the
e-mail response.

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00:17:41,080 --> 00:17:48,720
So anyway, 2 weeks later I I got
a note from Spaulding saying I

271
00:17:48,720 --> 00:17:53,920
could expect the offer of a
lectureship shortly, and sure

272
00:17:53,920 --> 00:17:57,880
enough, two or three days later
there was a formal note from the

273
00:17:58,160 --> 00:18:03,120
Registrar's department offering
me a position as a lecturer at

274
00:18:03,120 --> 00:18:07,120
the bottom of the lecturer
scale, which at the time was

275
00:18:07,760 --> 00:18:12,520
1400 lbs a year.
It didn't compare very well with

276
00:18:12,520 --> 00:18:16,320
what I could have earned in the
USA if I'd been eligible, but I

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00:18:16,320 --> 00:18:20,200
forget this was Imperial College
in London.

278
00:18:20,800 --> 00:18:26,480
I was also awarded London
Allowance and this was an extra

279
00:18:26,480 --> 00:18:32,520
£60 a year.
So I, I accepted like a shot and

280
00:18:32,520 --> 00:18:37,040
my early years at Imperial
College were, were were just

281
00:18:37,040 --> 00:18:39,880
delightful.
I'd really a very light teaching

282
00:18:39,880 --> 00:18:41,960
load, but an interesting
teaching load.

283
00:18:41,960 --> 00:18:45,840
It was a master's level course.
I was asked to take in fluid

284
00:18:45,840 --> 00:18:49,280
mechanics.
I had plenty of time free to try

285
00:18:49,280 --> 00:18:54,440
and get research students.
Sorry, research funding, but

286
00:18:54,560 --> 00:18:56,720
then I mentioned research
students.

287
00:18:56,880 --> 00:19:00,640
There was also an important
element there, Bran Spaulding

288
00:19:00,640 --> 00:19:03,320
said.
Would I take over as my

289
00:19:03,320 --> 00:19:09,200
administrative load the process
of research student admissions?

290
00:19:09,200 --> 00:19:14,160
It meant that I, I looked at all
the proposals that came in,

291
00:19:15,320 --> 00:19:18,760
collected further references if
these weren't provided,

292
00:19:18,760 --> 00:19:23,080
distributed the applications to
members of staff that I thought

293
00:19:23,080 --> 00:19:26,240
might be interested in taking
them and so on.

294
00:19:26,720 --> 00:19:30,840
But naturally I got first sight
of all of the students, and it

295
00:19:30,840 --> 00:19:37,720
was from that site that I was
able to recruit both Bill Jones

296
00:19:37,960 --> 00:19:43,120
and Kim Mohanulich the projects
as my first PhD students.

297
00:19:43,200 --> 00:19:48,240
Now, viewers may well have heard
of these names because they've

298
00:19:49,080 --> 00:19:53,800
they've both gone on to very
successful academic careers and

299
00:19:53,880 --> 00:19:56,520
published extensively in
Turbulence Modelling.

300
00:19:56,520 --> 00:19:58,680
Can I just ask you a question at
that point?

301
00:19:59,040 --> 00:19:59,920
Sure.
How?

302
00:20:00,000 --> 00:20:02,600
How did it feel to go back to
London?

303
00:20:03,000 --> 00:20:05,880
Because you've gone to Boston,
you've gone to MIT.

304
00:20:06,360 --> 00:20:10,560
Was it almost a nice feeling to
come back now as a lecturer, not

305
00:20:10,560 --> 00:20:15,320
as a student be teaching?
You know, how did it feel to

306
00:20:15,320 --> 00:20:17,480
come back there?
Did it feel like progression

307
00:20:17,480 --> 00:20:20,360
with Spaulding now as a fellow
member of the academic staff?

308
00:20:20,360 --> 00:20:25,680
I don't think I I felt was
terribly conscious of a change

309
00:20:25,680 --> 00:20:28,760
of status.
What I was aware of didn't,

310
00:20:28,800 --> 00:20:33,480
doesn't relate directly to your
question, but was that some of

311
00:20:33,480 --> 00:20:39,760
the research students whom I got
to know a bit while I was doing

312
00:20:39,760 --> 00:20:44,800
my final undergraduate year
experimental special tasks, they

313
00:20:44,800 --> 00:20:47,160
were still there working on
their pitch.

314
00:20:47,360 --> 00:20:52,520
So it very much brought home to
me sporting his comment that if

315
00:20:52,520 --> 00:20:54,960
you want a quick PhD, go
elsewhere.

316
00:20:54,960 --> 00:20:57,120
Yeah.
OK.

317
00:20:57,160 --> 00:20:59,680
OK.
So you sort of skipped ahead a

318
00:20:59,680 --> 00:21:01,680
little bit, almost, yeah.
Yeah.

319
00:21:04,320 --> 00:21:07,040
So how so how about, you know,
the research sort of project?

320
00:21:07,040 --> 00:21:10,800
How about with with Bill?
Jones, Bill Jones I basically

321
00:21:10,800 --> 00:21:16,280
continued PhD research, only we
arranged that he would simply

322
00:21:16,280 --> 00:21:20,360
look at one particular
configuration of acceleration

323
00:21:20,360 --> 00:21:24,040
and that was flow between
converging planes.

324
00:21:24,400 --> 00:21:28,040
What I mean by converging planes
is we measured the boundary

325
00:21:28,040 --> 00:21:31,280
layer developing on that surface
and the and the other wall just

326
00:21:31,280 --> 00:21:35,880
sloped like this.
It's a very special geometry so

327
00:21:35,880 --> 00:21:40,560
far as accelerating boundary
layers is concerned because the

328
00:21:40,560 --> 00:21:44,960
thickness of the boundary layer
goes down strictly in proportion

329
00:21:45,160 --> 00:21:48,520
to the velocity going up.
So the Reynolds number of the

330
00:21:48,520 --> 00:21:53,120
flow reaches an equilibrium in
which it stays constant

331
00:21:53,120 --> 00:21:57,320
thereafter and also the
acceleration parameter

332
00:21:57,320 --> 00:22:01,440
determining the reversion to
laminar flow that also stays

333
00:22:01,440 --> 00:22:03,760
constant.
And what we discovered there

334
00:22:03,760 --> 00:22:08,400
that there wasn't just a single
point first of all for various

335
00:22:08,400 --> 00:22:12,440
levels of the acceleration
parameter, you actually got a

336
00:22:12,440 --> 00:22:18,400
frozen boundary layer was
dissimilar from a turbulent

337
00:22:18,400 --> 00:22:20,960
boundary layer.
And this the viscous sub layer

338
00:22:20,960 --> 00:22:24,560
was getting progressively
thicker and thicker in what was

339
00:22:24,560 --> 00:22:29,640
still a turbulent flow, a self
preserving turbulent flow until

340
00:22:29,640 --> 00:22:32,400
you reached a critical
acceleration.

341
00:22:33,440 --> 00:22:37,200
And at that level it you had a
complete collapsed to turbulent

342
00:22:37,200 --> 00:22:41,280
flow.
So a a lot more came out from

343
00:22:41,480 --> 00:22:45,080
from Bill Jones's study than I
had I had achieved.

344
00:22:45,280 --> 00:22:50,400
As for chemo, we actually looked
at a project sponsored by the

345
00:22:50,400 --> 00:22:54,160
Berkeley Nuclear Labs.
They asked us to determine

346
00:22:54,160 --> 00:22:58,280
whether for flying a duct,
whether the position where the

347
00:22:58,280 --> 00:23:03,240
velocity reached its maximum
would coincide with where the

348
00:23:03,400 --> 00:23:05,720
turbulent shear stress fell to
0.

349
00:23:06,720 --> 00:23:10,560
They'd been doing tests
themselves in flow through

350
00:23:10,560 --> 00:23:14,360
annually with a rough inner core
tube and a smooth outer

351
00:23:14,360 --> 00:23:19,680
containing tube and had assumed
that there was this coincidence

352
00:23:19,680 --> 00:23:24,840
and it gave them very hard to
understand values for the

353
00:23:24,840 --> 00:23:29,320
respective shear stresses on the
rough and the smooth surface.

354
00:23:29,480 --> 00:23:32,520
Could we sort it out, Judy?
We did we he didn't look at an

355
00:23:32,520 --> 00:23:37,800
annulus, we looked at parallel
flow between parallel plates and

356
00:23:37,800 --> 00:23:40,000
found there was a huge
difference.

357
00:23:40,000 --> 00:23:45,120
That was a thesis very well,
very well completed by Kimo.

358
00:23:45,440 --> 00:23:49,920
Now I think the next point I
should mention was research that

359
00:23:50,120 --> 00:23:56,080
Brian Spalding and his brilliant
student Suhas Patanka had done.

360
00:23:56,440 --> 00:24:02,000
They produced a very efficient,
very easy to use boundary layer

361
00:24:02,000 --> 00:24:05,560
code.
The only thing that it was weak

362
00:24:05,560 --> 00:24:09,480
on was its model of turbulence.
It it had the mixing length

363
00:24:09,480 --> 00:24:13,840
hypothesis.
Prandtl's 1925 paper In There

364
00:24:15,800 --> 00:24:19,920
Sporting realised that what he
needed was a much more

365
00:24:19,920 --> 00:24:25,480
sophisticated model, one that
had individual velocity and

366
00:24:25,480 --> 00:24:29,640
length scales of turbulence
available, and not only the

367
00:24:29,640 --> 00:24:35,040
these scales would be affected
by diffusion, convection and

368
00:24:35,040 --> 00:24:40,200
various source and sync terms.
So he'd obviously chosen the

369
00:24:40,200 --> 00:24:41,920
turbulence energy as one of
them.

370
00:24:42,680 --> 00:24:46,440
But then there was the issue of
what would you use to get the

371
00:24:46,440 --> 00:24:50,600
turbulent length scale didn't
have to be the length scale

372
00:24:50,600 --> 00:24:54,800
itself because you already were
solving a transport equation for

373
00:24:54,800 --> 00:25:00,000
the kinetic energy K.
So any combination of K with L

374
00:25:00,000 --> 00:25:02,680
would be a possibility.
Indeed.

375
00:25:02,680 --> 00:25:08,840
Golf gang Rody Sporting student
adopted the product of K * L

376
00:25:08,840 --> 00:25:12,920
where whereas Brian Sporting
himself had an individual

377
00:25:12,920 --> 00:25:17,680
project underway and he chose
something he called you, which

378
00:25:18,400 --> 00:25:22,600
basically amounted to K divided
by the square of length scale.

379
00:25:22,800 --> 00:25:27,240
OK, well one day Spaulding said
to me, hey, would you like to

380
00:25:27,240 --> 00:25:32,880
join our group?
I put it to Bill and Kimmo and

381
00:25:32,880 --> 00:25:34,960
they thought that sounded a neat
idea.

382
00:25:34,960 --> 00:25:38,760
By then we'd started to explore
elaborations of the mixing

383
00:25:38,760 --> 00:25:41,960
length hypothesis, but although
we've published several papers

384
00:25:41,960 --> 00:25:44,600
on the topic, it clearly wasn't
going to get anywhere.

385
00:25:44,600 --> 00:25:48,360
So one thing I should say
though, is that Kimohaneilich

386
00:25:49,320 --> 00:25:53,280
came from Yugoslavia and
Yugoslavia was a communist

387
00:25:53,280 --> 00:25:56,440
country at the time.
Naturally then he had learned

388
00:25:56,440 --> 00:26:01,760
Russian in school and that meant
he could, he could have ready

389
00:26:01,760 --> 00:26:06,360
access to the Russian literature
and came across a paper by

390
00:26:06,400 --> 00:26:12,320
somebody called Davidoff, which
advocated in an otherwise

391
00:26:12,320 --> 00:26:16,680
totally unusable turbulence
model, but it advocated the use

392
00:26:16,680 --> 00:26:21,320
of epsilon, the energy
dissipation rate, OK, of, of

393
00:26:21,320 --> 00:26:24,720
turbulence that appealed to us
just physically.

394
00:26:24,720 --> 00:26:29,040
It was something that one could
put one's hand on and hopefully

395
00:26:29,040 --> 00:26:31,600
one day be able to measure
accurately.

396
00:26:33,520 --> 00:26:41,040
And thus that was what we chose.
We produced that, I say we, but

397
00:26:41,280 --> 00:26:45,280
I was sitting back, it was my
research students that that were

398
00:26:45,280 --> 00:26:49,400
doing the computation.
We produced the version of that

399
00:26:49,800 --> 00:26:55,920
and we're delighted to discover
that precisely the same model

400
00:26:56,560 --> 00:27:02,600
enabled us to compute both the
free flows, that is to say of of

401
00:27:02,840 --> 00:27:08,400
mixing layer or a plane jet, but
with the same model that we used

402
00:27:08,560 --> 00:27:11,320
to compute flow along a flat
plate.

403
00:27:11,320 --> 00:27:17,280
Neither of the options that
Spalding and Rhody were using

404
00:27:17,920 --> 00:27:22,280
achieved that.
So it it was indeed real

405
00:27:22,280 --> 00:27:25,040
progress.
And fairly soon thereafter,

406
00:27:25,040 --> 00:27:29,440
Brian Spalding advocated that
the group's work should focus on

407
00:27:29,440 --> 00:27:33,640
what he called the K epsilon
model rather than either of the

408
00:27:33,640 --> 00:27:37,760
alternatives.
Of course, this model that we

409
00:27:37,800 --> 00:27:42,280
arrived at, the K epsilon Eddy
viscosity model, wasn't any good

410
00:27:42,280 --> 00:27:45,600
as it stood for either Bill or
Kimo's research.

411
00:27:45,680 --> 00:27:51,080
It needed great extension.
For example, in Bill's case, he

412
00:27:51,080 --> 00:27:55,360
had to deal with situations
where one started with a

413
00:27:55,360 --> 00:27:59,440
turbulent boundary layer and it
went back to or towards lamina.

414
00:27:59,880 --> 00:28:04,480
And so with the inner boundary
condition that was being used

415
00:28:04,480 --> 00:28:08,360
next to the wall wasn't strictly
a wall boundary condition.

416
00:28:08,520 --> 00:28:11,880
It assumed that across the
viscous sub layer there was a

417
00:28:11,880 --> 00:28:16,000
universal velocity profile.
And so we didn't need to go

418
00:28:16,000 --> 00:28:19,360
actually to the wall.
We'd make our boundary condition

419
00:28:19,640 --> 00:28:23,840
out in the fully turbulent
region just a millimetre or so

420
00:28:24,000 --> 00:28:27,440
from the wall.
That meant that he had to

421
00:28:27,440 --> 00:28:32,600
develop and extend his model and
it it was a major task so that

422
00:28:32,600 --> 00:28:38,480
it included all semi viscous
effects that would modify both

423
00:28:38,480 --> 00:28:43,200
kinetic energy that that wasn't
that difficult, but also also

424
00:28:43,280 --> 00:28:46,400
energy dissipation rate.
And this one was flying blind.

425
00:28:46,400 --> 00:28:50,360
There was no experience in this.
So he, he did a very good job

426
00:28:50,720 --> 00:28:54,760
and I'm glad to say that the
paper he and I produced

427
00:28:54,840 --> 00:29:00,080
describing it as being cited a
large number of times over 6000.

428
00:29:00,080 --> 00:29:06,240
I think likewise for chemo, he
had been asked by sponsors to

429
00:29:06,560 --> 00:29:11,240
explain or indeed provide a
model for situations where the

430
00:29:11,240 --> 00:29:16,320
position of maximum velocity did
not coincide with the position

431
00:29:16,320 --> 00:29:19,200
of 0 shear stress.
But of course with an Eddy

432
00:29:19,200 --> 00:29:21,440
viscosity model, you can't do
that.

433
00:29:21,440 --> 00:29:25,480
They're linked by the definitive
link interlinkage between the

434
00:29:25,920 --> 00:29:29,120
mean field velocity gradient and
the turbulent shear stress.

435
00:29:29,120 --> 00:29:35,200
So there what we did was provide
an additional independent

436
00:29:35,520 --> 00:29:38,440
transport equation for the
turbulent stress.

437
00:29:38,440 --> 00:29:43,920
Again, that paper has been
reasonably widely cited.

438
00:29:44,160 --> 00:29:50,600
I think both Kimmo and Bill and
I felt at the times, though,

439
00:29:50,600 --> 00:29:55,960
that Eddie viscosity modelling
wasn't the way to go for most

440
00:29:55,960 --> 00:29:59,440
cases.
We felt that you really needed

441
00:29:59,440 --> 00:30:03,040
to solve transport equations for
all the Reynolds stresses

442
00:30:03,080 --> 00:30:05,760
independently of the velocity
field.

443
00:30:05,880 --> 00:30:11,680
And curiously enough, Brian
Spalding was the agent enabling

444
00:30:11,680 --> 00:30:17,600
me to pursue that work.
Golf Gang Roadie by then had

445
00:30:17,600 --> 00:30:23,160
completed all his computations,
but he was in the throes of

446
00:30:23,400 --> 00:30:27,960
trying to write a thesis that
met his supervisors very

447
00:30:27,960 --> 00:30:33,120
exacting standards in English.
His scholarship had run out by

448
00:30:33,120 --> 00:30:40,080
then and so I was able to hire
him as a a quasi postdoctoral

449
00:30:40,160 --> 00:30:45,280
fellow and together we worked on
developing a full stress

450
00:30:45,280 --> 00:30:49,440
transport model.
And in the time available that

451
00:30:49,440 --> 00:30:54,920
also went very, very well.
We produced a solver that

452
00:30:55,360 --> 00:31:00,120
nowadays known as the LRR model
Londores and Roadie in

453
00:31:00,120 --> 00:31:05,800
alphabetical order.
I'd I didn't so, and that too

454
00:31:05,800 --> 00:31:08,840
has been quite widely cited.
I think that's a little bit of

455
00:31:08,840 --> 00:31:12,040
an understatement.
I think they're quite widely

456
00:31:12,040 --> 00:31:14,320
used.
And maybe you just forward maybe

457
00:31:14,320 --> 00:31:17,440
getting on to the next point,
just on this chapter, I guess

458
00:31:17,640 --> 00:31:21,040
would it be fair to say for
people to realize that all of

459
00:31:21,040 --> 00:31:26,520
the work prior to Spalding's
finite volume code was

460
00:31:26,520 --> 00:31:30,520
essentially experimental and you
were mainly deriving

461
00:31:31,360 --> 00:31:34,200
relationships from the
experimental data, There wasn't

462
00:31:34,200 --> 00:31:38,120
as much coding or numerical
simulation work.

463
00:31:38,200 --> 00:31:44,240
Is that correct?
It was I'd say 80 to 90% correct

464
00:31:44,800 --> 00:31:47,520
there.
There was work on developing

465
00:31:47,520 --> 00:31:54,280
solvers people in the in the the
USA was were on to on to that a

466
00:31:54,280 --> 00:31:57,400
group at Los Alamos.
There were others in England.

467
00:31:57,400 --> 00:32:01,280
You mustn't forget Peter
Bradshaw also, although he was

468
00:32:01,320 --> 00:32:04,800
out and out an experimentalist.
He worked with a group at the

469
00:32:04,800 --> 00:32:08,960
National Physical Laboratory
that included some numerical

470
00:32:08,960 --> 00:32:13,680
fluid mechanisms and they
developed a scheme usually

471
00:32:13,680 --> 00:32:19,000
called Bradshaw's method that
indeed at the 1968 Stanford

472
00:32:19,000 --> 00:32:23,800
conference was rather more
successful than sporting and

473
00:32:23,800 --> 00:32:27,200
Patanka scheme with that had
used the mixing length

474
00:32:27,200 --> 00:32:32,160
hypothesis, of course.
OK, So the this bringing

475
00:32:32,160 --> 00:32:35,200
together, how did it work in
practice at that point?

476
00:32:35,200 --> 00:32:38,800
Was Spalding still essentially
running the department?

477
00:32:38,880 --> 00:32:42,480
And and so in some ways was that
the slight you still had your

478
00:32:42,480 --> 00:32:46,520
individual research groups, but
you were sort of merging in one,

479
00:32:46,520 --> 00:32:48,640
you know, what was that?
Because I can imagine he is the

480
00:32:48,640 --> 00:32:52,080
senior professor here.
You you're the How did that

481
00:32:52,080 --> 00:32:55,600
relationship at that point?
Well, well, Sporting was never a

482
00:32:55,600 --> 00:32:58,640
head of department.
He was happy to be head of the

483
00:32:58,840 --> 00:33:04,360
heat transfer section, OK,
really the next, and he was

484
00:33:04,360 --> 00:33:09,520
happy doing that.
The next major change in my own

485
00:33:09,520 --> 00:33:14,960
career also arose indirectly
from Brian Spaulding with the

486
00:33:15,040 --> 00:33:18,000
success of this new boundary
layer code.

487
00:33:18,200 --> 00:33:21,920
And he had another code that
handled recirculating flows too.

488
00:33:23,160 --> 00:33:27,960
There was a lot of interest
outside of the university in

489
00:33:28,160 --> 00:33:34,000
getting consultancy help on
applying these new schemes to

490
00:33:34,000 --> 00:33:37,840
flows that were of interest to
the people in question.

491
00:33:37,960 --> 00:33:41,280
Sporting initially tried
handling that internally by

492
00:33:41,280 --> 00:33:46,800
sharing tasks with trusted
members of staff and they're

493
00:33:46,840 --> 00:33:50,680
research students.
But after a year or so, he he

494
00:33:50,680 --> 00:33:55,080
just felt that wasn't working.
He'd find somewhere outside of

495
00:33:55,080 --> 00:33:59,240
the university.
So he established an independent

496
00:33:59,240 --> 00:34:04,440
company, Concentration, Heat and
Momentum, or Cham for short.

497
00:34:04,440 --> 00:34:09,320
It established headquarters in
Wimbledon and then he had the

498
00:34:09,320 --> 00:34:16,280
enormous task of recruiting
staff, completing the various

499
00:34:16,760 --> 00:34:19,280
consultancy requests that were
coming in.

500
00:34:19,280 --> 00:34:25,520
And inevitably, even for someone
as able as him, the activity

501
00:34:25,520 --> 00:34:30,400
within the university itself,
his academic role, they'd they

502
00:34:30,400 --> 00:34:38,400
very much were on hold and this
this produced unhappiness with

503
00:34:38,679 --> 00:34:44,560
within the department.
Now, as it happened, one of the

504
00:34:45,000 --> 00:34:48,600
Spalding's group had also been
made a professor by then.

505
00:34:49,080 --> 00:34:53,400
His name was Jim Whitelaw.
He was an experimentalist in

506
00:34:53,400 --> 00:34:58,240
fluid mechanics mainly, but the
idea developed that since he was

507
00:34:58,240 --> 00:35:02,440
a professor, he was eligible to
basically to lead a group of

508
00:35:02,440 --> 00:35:05,200
staff.
Maybe the head of department

509
00:35:05,200 --> 00:35:08,680
would form something called the
fluid section, and those who

510
00:35:08,680 --> 00:35:13,680
wanted would transfer their
affinity from the heat transfer

511
00:35:13,680 --> 00:35:17,240
section to the fluid section.
What was the outcome of that?

512
00:35:17,240 --> 00:35:22,400
You can guess absolute turmoil.
I won't go into the details of

513
00:35:22,400 --> 00:35:26,520
the battling, but essentially it
brought research to a halt.

514
00:35:26,600 --> 00:35:32,400
Then one day I had a telephone
call from the USA.

515
00:35:32,520 --> 00:35:35,360
It was from the head of
department at the University of

516
00:35:35,360 --> 00:35:39,480
California, Davis.
He'd been on sabbatical leave

517
00:35:39,560 --> 00:35:42,960
within Spalding's Group A couple
of years before.

518
00:35:43,040 --> 00:35:45,480
He and I had got to know each
other somewhat.

519
00:35:45,600 --> 00:35:50,720
So he called and he said
something like, hey, Bran, I

520
00:35:51,000 --> 00:35:56,160
really sorry to hear about the
problems that you guys have got

521
00:35:56,160 --> 00:36:00,200
in the department at the moment.
I've been talking with the Dean

522
00:36:00,200 --> 00:36:05,360
and he said to me that if I
wanted to offer you a full

523
00:36:05,360 --> 00:36:08,800
professorship to come here to
Davis, that was that.

524
00:36:09,480 --> 00:36:13,920
Would you be interested?
I heard these words and just

525
00:36:13,920 --> 00:36:17,800
just seemed like someone had I
was drowning and that someone

526
00:36:17,800 --> 00:36:21,760
had dropped a lifeline from a
helicopter to pull me out of the

527
00:36:23,520 --> 00:36:26,520
So we I said yes without
hesitation.

528
00:36:26,520 --> 00:36:32,120
It took maybe well, we didn't
get, didn't arrive in Davis

529
00:36:32,120 --> 00:36:39,160
until, well, I think it was 96,
the summer of 1976, but we were

530
00:36:39,160 --> 00:36:41,200
very pleased to get there at the
time.

531
00:36:41,480 --> 00:36:46,080
What was it, what was it like
though with your family,

532
00:36:46,080 --> 00:36:48,120
children?
Was that and that was a big

533
00:36:48,120 --> 00:36:52,040
move, you know, big thing to
move to the US, to leave London.

534
00:36:52,680 --> 00:36:56,040
Was it an excitement to do it in
a way?

535
00:36:56,040 --> 00:37:00,280
Was it a challenge to convince
your wife and family to to go

536
00:37:00,280 --> 00:37:04,800
with you?
With my, my wife, she's Danish

537
00:37:04,800 --> 00:37:09,560
and moving away from moving away
from Europe was a big thing for

538
00:37:09,560 --> 00:37:15,000
her.
And I softened that by buying,

539
00:37:15,640 --> 00:37:21,600
buying a property in France.
My contractor Davis was for nine

540
00:37:21,600 --> 00:37:26,520
months, that is to say just just
just until June and then you

541
00:37:26,520 --> 00:37:29,080
were free completely over the
summer.

542
00:37:29,160 --> 00:37:33,800
And I'd have to say also that
unlike, unlike Imperial College

543
00:37:33,800 --> 00:37:37,800
that I just come out of staff
didn't have administrative work

544
00:37:37,800 --> 00:37:41,440
to do.
There was other other workers

545
00:37:41,440 --> 00:37:44,760
that handled all the
administration academics were

546
00:37:44,760 --> 00:37:47,320
there just to teach and do
research.

547
00:37:47,840 --> 00:37:52,520
So it did make sense having this
nine month contract.

548
00:37:52,520 --> 00:38:00,920
So what I agreed we do was in in
the summer months, we, we come

549
00:38:01,440 --> 00:38:04,560
to Europe entirely, which would
give her more opportunity to

550
00:38:04,560 --> 00:38:08,920
interact with friends and and so
on.

551
00:38:09,800 --> 00:38:13,600
Yes, we bought a rundown.
We bought a rundown farmhouse

552
00:38:13,600 --> 00:38:22,080
just north of Lyon and in the in
the summer I would would drop in

553
00:38:22,440 --> 00:38:27,600
two or three times a week to the
acre Santral Polytechnique in

554
00:38:27,840 --> 00:38:33,840
Lyon in enjoying doing research
with new colleagues there.

555
00:38:33,840 --> 00:38:38,520
My wife was happy at our our
rather dilapidated farmhouse,

556
00:38:38,520 --> 00:38:41,360
but that was that was a
different life.

557
00:38:41,360 --> 00:38:49,240
So, so yes, we will make that.
But what about UC Davis then?

558
00:38:49,240 --> 00:38:52,200
What was it like there?
Well, the department was about

559
00:38:52,200 --> 00:38:54,960
half the size of Imperial
College.

560
00:38:55,080 --> 00:38:57,880
Colleges staff did a lot more
teaching.

561
00:38:57,880 --> 00:39:00,680
They didn't have administration
to do, but they certainly did a

562
00:39:00,680 --> 00:39:02,920
lot more teaching.
And some of them treated

563
00:39:02,920 --> 00:39:07,920
research really like a hobby,
something that they'd squeeze in

564
00:39:07,920 --> 00:39:11,960
when time allowed.
Luckily I struck up a very good

565
00:39:11,960 --> 00:39:16,720
working relationship with two
staff there that really they

566
00:39:16,720 --> 00:39:20,560
were experimentalists in various
aspects of heat transfer and

567
00:39:20,560 --> 00:39:25,680
they they invited me to join
them to add a computational side

568
00:39:25,680 --> 00:39:28,400
to their activity.
Probably the main thing though

569
00:39:28,400 --> 00:39:32,680
that I should should mention is
that Onira, which is the French

570
00:39:32,680 --> 00:39:38,640
equivalent of NASA Onira, sent a
post doc who had done his

571
00:39:38,640 --> 00:39:42,760
doctorate in in turbulence
modelling to work with me for a

572
00:39:42,760 --> 00:39:44,320
year.
I guess they thought that the

573
00:39:44,320 --> 00:39:47,640
interaction of the two of us
might be useful.

574
00:39:47,800 --> 00:39:53,280
What he had done was produce an
equation, sorry, a turbulence

575
00:39:53,280 --> 00:39:58,760
model not with one length scale,
but two effectively length scale

576
00:39:58,760 --> 00:40:01,960
equations that are used in
different ways in his model.

577
00:40:02,000 --> 00:40:06,160
I didn't find the model as
presented in his thesis exactly

578
00:40:06,160 --> 00:40:09,960
coherent.
But we work together and agreed

579
00:40:09,960 --> 00:40:14,360
that what we do would be to
develop what's known as a multi

580
00:40:14,360 --> 00:40:18,040
scale model.
That is to say, we'd effectively

581
00:40:18,200 --> 00:40:22,920
cut the turbulent spectrum in
half with a large scale part in

582
00:40:22,920 --> 00:40:29,680
which eddies would capture mean
energy from the from the flow

583
00:40:29,680 --> 00:40:35,880
and a medium and fine scale part
that received energy from the

584
00:40:36,320 --> 00:40:39,120
large scale turbulence and
finally dissipated it.

585
00:40:39,120 --> 00:40:43,120
That is so we had separate
transport equations for the two

586
00:40:43,120 --> 00:40:46,280
parts of turbulence.
Davis didn't have a great

587
00:40:46,280 --> 00:40:49,480
computing system.
We could only look at simple

588
00:40:49,480 --> 00:40:53,400
flows, which also suited very
well the background of the

589
00:40:53,520 --> 00:40:56,840
French visitor.
So we looked at sudden

590
00:40:56,880 --> 00:40:58,920
contractions, sudden
distortions.

591
00:40:58,920 --> 00:41:02,200
They were just, these were just
one-dimensional flows.

592
00:41:02,480 --> 00:41:07,000
You could almost calculate them
by hand rather than using the

593
00:41:07,000 --> 00:41:12,080
computer.
Well anyway, the outcome of this

594
00:41:12,080 --> 00:41:16,800
was I felt quite spectacular.
The simple flows which we did a

595
00:41:16,840 --> 00:41:21,920
so so job on with previous
models were now much better

596
00:41:21,920 --> 00:41:25,520
predicted.
You got a delayed response when

597
00:41:25,520 --> 00:41:29,000
you put new energy in.
You didn't get the dissipation

598
00:41:29,000 --> 00:41:33,160
rate occurring straight away.
There was a delayed response and

599
00:41:33,160 --> 00:41:37,120
that mimicked very well the
experiments that more or less

600
00:41:37,120 --> 00:41:38,920
brought us to the end of his
year.

601
00:41:38,920 --> 00:41:43,640
But I wanted to continue the
research to include really the

602
00:41:43,640 --> 00:41:46,760
sorts of flows that in
engineering 1 is dealing with

603
00:41:47,080 --> 00:41:51,280
boundary layers, mixing layers,
jets, wakes this, that and the

604
00:41:51,320 --> 00:41:53,320
other.
But in order to do that, the

605
00:41:53,920 --> 00:41:56,560
Davis system wasn't really
suitable.

606
00:41:56,560 --> 00:42:01,000
That is to say, the computer
gave too slow turn around for

607
00:42:01,000 --> 00:42:05,120
model development.
Also, well, I needed to get

608
00:42:05,640 --> 00:42:08,120
funding if I was to get anyone
else.

609
00:42:08,200 --> 00:42:11,800
I couldn't easily recruit
research students at Davis.

610
00:42:11,800 --> 00:42:14,640
They didn't seem to want to do
research in turbulence

611
00:42:14,640 --> 00:42:19,080
modelling.
But Kimo Hanielich, I knew, was

612
00:42:19,080 --> 00:42:22,280
struggling with the
administration that had hit him.

613
00:42:22,280 --> 00:42:27,720
And having got funding from
NASA, I invited him to come over

614
00:42:27,720 --> 00:42:32,800
for a year and join me.
Now, as I say, the Davis

615
00:42:32,800 --> 00:42:36,440
computing system wasn't up to
it, but it wasn't difficult to

616
00:42:36,440 --> 00:42:41,160
obtain computing resources at
the the Lawrence Berkeley labs.

617
00:42:41,200 --> 00:42:45,360
Now in those days, we're still
talking about the 1970s.

618
00:42:45,360 --> 00:42:47,640
You've you've got computing
resources.

619
00:42:48,240 --> 00:42:51,880
Laptops weren't invented and you
sure didn't have anything called

620
00:42:51,880 --> 00:42:55,600
remote access.
In order to use these, one had

621
00:42:55,600 --> 00:43:00,680
to get in one's car and drive
the 60 miles or so down to the

622
00:43:00,680 --> 00:43:05,040
Lawrence Berkeley labs, which
had brilliant facilities at the

623
00:43:05,040 --> 00:43:09,320
time.
Well, Kimo mainly, but I, I in

624
00:43:09,320 --> 00:43:13,040
joined in as well, worked on
this problem for the best part

625
00:43:13,040 --> 00:43:16,720
of a year.
And I have to say the outcome

626
00:43:16,720 --> 00:43:22,200
was disappointing.
We made one or two improvements

627
00:43:22,200 --> 00:43:25,480
that applied equally to single
scale models.

628
00:43:25,480 --> 00:43:29,200
But there was really in you,
you're looking at flows like a

629
00:43:29,200 --> 00:43:33,600
mixing layer where so much
energy is captured from the mean

630
00:43:33,600 --> 00:43:38,120
flow into the turbulence that
the medium and fine scale part

631
00:43:38,120 --> 00:43:40,560
of the spectrum hardly had a
look in.

632
00:43:40,560 --> 00:43:46,120
So the results that we got for
these flows were only marginally

633
00:43:46,120 --> 00:43:50,600
better than we had obtained with
a single scale model.

634
00:43:51,400 --> 00:43:55,520
End of story.
I thought it worth mentioning

635
00:43:55,520 --> 00:44:00,840
that because this brings home
that what looked like very good

636
00:44:00,840 --> 00:44:04,240
research directions sometimes
don't don't work.

637
00:44:05,360 --> 00:44:08,120
Which is, which is a good lesson
for people, I guess.

638
00:44:08,120 --> 00:44:11,920
Maybe you're well known for your
successes with the KEP silent

639
00:44:11,920 --> 00:44:14,440
model and the LLR.
But I guess if the point is not

640
00:44:14,440 --> 00:44:16,680
all research comes out in
success.

641
00:44:16,880 --> 00:44:19,200
But maybe that's the point of
research, isn't it?

642
00:44:19,440 --> 00:44:21,280
Some stuff works.
Indeed doesn't.

643
00:44:21,280 --> 00:44:23,720
Yes.
Well, there was something else

644
00:44:23,720 --> 00:44:28,360
that arose from these trips down
to Berkeley, because I got to

645
00:44:28,360 --> 00:44:32,480
know the head of department at
the University of California,

646
00:44:32,480 --> 00:44:35,240
Berkeley.
And one day he he said to me,

647
00:44:35,400 --> 00:44:39,200
listen, I see you're down here
quite regularly.

648
00:44:39,240 --> 00:44:44,240
We need someone to teach
turbulence modelling to our our

649
00:44:44,320 --> 00:44:47,880
students here.
And there are students asking to

650
00:44:47,880 --> 00:44:52,080
do research in that area, but we
really don't have anyone that

651
00:44:52,080 --> 00:44:56,560
could provide that role.
What if we, we're in the same

652
00:44:56,560 --> 00:45:02,640
university system as Davis?
What if we arrange to hire you

653
00:45:02,640 --> 00:45:05,920
for, let's say, one day a week?
It would be very easy to

654
00:45:05,920 --> 00:45:08,080
arrange.
And then when you're down here

655
00:45:08,960 --> 00:45:13,480
at the LBL, you could also call
in here at the department, see

656
00:45:13,480 --> 00:45:17,480
students, give a lecture or two.
And it seemed to me that that

657
00:45:17,800 --> 00:45:22,080
that would work well.
Again, I was delighted at this

658
00:45:22,080 --> 00:45:23,960
suggestion.
Couldn't wait to get back to

659
00:45:23,960 --> 00:45:27,880
Davis to break the good news to
the head of department so he

660
00:45:27,880 --> 00:45:32,520
could then just sign whatever
forms were needed to bring the

661
00:45:32,520 --> 00:45:35,800
change about.
I told him and he said

662
00:45:36,280 --> 00:45:39,880
absolutely not.
If students know they can work

663
00:45:39,880 --> 00:45:43,040
with you by going to Berkeley,
they're not going to come to

664
00:45:43,040 --> 00:45:45,760
Davis.
I said to him, Alan, that that

665
00:45:45,760 --> 00:45:48,960
doesn't make sense, it's because
they won't come to Davis.

666
00:45:49,200 --> 00:45:52,720
But I can.
I can see great opportunities

667
00:45:52,720 --> 00:45:55,520
from recruiting students in in
Berkeley.

668
00:45:55,960 --> 00:46:01,080
However, he was implacably
opposed and I accepted it.

669
00:46:01,080 --> 00:46:05,080
I liked life in California.
It was was a bitter pill, but I

670
00:46:05,080 --> 00:46:09,040
could swallow it.
But then not very long later, I

671
00:46:09,040 --> 00:46:14,920
got a phone call from England.
It was the principle of humis,

672
00:46:14,920 --> 00:46:18,000
that is to say Manchester's
Institute of Science and

673
00:46:18,000 --> 00:46:20,800
Technology.
He said the head of thermofluids

674
00:46:20,800 --> 00:46:25,200
here has died and we're looking
to recruit his replacement.

675
00:46:25,360 --> 00:46:28,000
A few people I've asked have
suggested you might be

676
00:46:28,000 --> 00:46:31,480
interested.
I disabused him of of that idea.

677
00:46:31,480 --> 00:46:36,560
I said listen, I've only been
here for 2 1/2 years, I put in a

678
00:46:36,560 --> 00:46:38,600
lot of effort.
I haven't started reaping the

679
00:46:38,600 --> 00:46:43,640
rewards of being here so it's
it's too early for me to

680
00:46:43,640 --> 00:46:48,240
consider coming.
However, he kept persisting and

681
00:46:48,240 --> 00:46:51,560
in the end I thought I'll take a
short back trip back to England,

682
00:46:51,640 --> 00:46:55,040
see my parents, haven't seen
them for a while, then I'll go

683
00:46:55,040 --> 00:46:58,960
up to Manchester, have the
interview and I'll politely

684
00:46:58,960 --> 00:47:02,600
decline if they offer me a
position and life will return to

685
00:47:02,600 --> 00:47:05,920
normal.
And that was the plan that I put

686
00:47:05,920 --> 00:47:08,520
into motion.
Spent a pleasant weekend with my

687
00:47:08,520 --> 00:47:14,000
parents, travelled to Manchester
and had a whole day before the

688
00:47:14,000 --> 00:47:19,360
interview to be exposed to what
you miss could offer.

689
00:47:19,360 --> 00:47:23,280
And I have to say Neil, I was
just blown away.

690
00:47:24,200 --> 00:47:28,400
First of all, Thermo fluids
research had its own building

691
00:47:28,480 --> 00:47:34,960
all through itself.
It had 15 academic staff that I

692
00:47:34,960 --> 00:47:40,160
would generally have
responsibility for, but not just

693
00:47:40,280 --> 00:47:45,040
academic staff.
There must have been at least 30

694
00:47:45,280 --> 00:47:50,240
technician staff and what are
called experimental officers to

695
00:47:50,240 --> 00:47:52,680
basically help push research
along.

696
00:47:52,920 --> 00:47:57,760
There were around computing
staff, of course, at the end.

697
00:47:58,120 --> 00:48:02,240
At this point in time everyone
was using card decks and it

698
00:48:02,240 --> 00:48:05,240
needed it, needed quite a lot of
support.

699
00:48:05,480 --> 00:48:09,480
But four or five full time
positions, That was amazing.

700
00:48:09,480 --> 00:48:13,840
Finally, at the end of the day,
I had an interview with the

701
00:48:14,480 --> 00:48:19,080
principal himself.
It was a relaxed chat really

702
00:48:19,080 --> 00:48:25,520
over a glass of Sherry I recall.
And he said, of course, if you

703
00:48:25,520 --> 00:48:28,040
do come here, there will be
administrative work you won't

704
00:48:28,040 --> 00:48:32,960
need to get involved in.
And to make it easier for you,

705
00:48:33,840 --> 00:48:38,760
you'll have a dowry appointment.
Meaning that I could choose

706
00:48:38,800 --> 00:48:43,680
anyone that I thought was would
going to be helpful to come and

707
00:48:43,680 --> 00:48:46,720
work as a lecturer.
No interview, no anything.

708
00:48:46,720 --> 00:48:50,560
It was just me saying I want to
have him.

709
00:48:51,240 --> 00:48:56,640
It probably runs counter to to
in nowadays, but it didn't at

710
00:48:56,640 --> 00:49:00,960
that time.
So at the end of that I had to

711
00:49:00,960 --> 00:49:05,440
say I really wanted the
interview the next day to go as

712
00:49:05,440 --> 00:49:07,920
well.
And it was a disaster.

713
00:49:08,400 --> 00:49:12,800
I was taken into the room itself
where the interview was

714
00:49:12,800 --> 00:49:17,040
conducted.
In front of me was a huge Oval

715
00:49:17,040 --> 00:49:20,240
table.
I was sat on one side of the

716
00:49:20,240 --> 00:49:28,000
table and ranged all around the
other side were the questioners.

717
00:49:28,000 --> 00:49:31,920
There were about 10 or 12 there.
The principal was there.

718
00:49:31,920 --> 00:49:38,280
He introduced me, welcomed me,
introduced me to the other.

719
00:49:38,880 --> 00:49:42,760
Other people on the panel think
he maybe even asked me a couple

720
00:49:42,760 --> 00:49:44,600
of soft questions which I dealt
with.

721
00:49:44,600 --> 00:49:49,400
But then he stepped back and
turned me loose to these hyenas

722
00:49:49,600 --> 00:49:54,040
that ravaged me for the next 50
minutes or so.

723
00:49:54,040 --> 00:49:57,320
They were obsessed with
something called the Finniston

724
00:49:57,320 --> 00:50:02,320
Report, a report, a government
produced report by Lord

725
00:50:02,320 --> 00:50:08,320
Finniston or whoever that looked
at potential changes in the

726
00:50:08,480 --> 00:50:10,640
training and development of
engineers.

727
00:50:10,640 --> 00:50:14,720
I think by then it had been
recognized that Britain didn't

728
00:50:14,720 --> 00:50:18,240
recognize engineers to the
extent that someone somewhere

729
00:50:18,240 --> 00:50:22,000
like Germany or Japan did.
And of course these these

730
00:50:22,000 --> 00:50:25,960
countries, despite the set back
of the Second World War, were

731
00:50:26,040 --> 00:50:30,480
already very advanced and
overtaking other European

732
00:50:30,480 --> 00:50:34,120
countries.
I honestly, I've been in America

733
00:50:34,120 --> 00:50:38,480
for 2 1/2 years.
I didn't have a clue about what

734
00:50:38,480 --> 00:50:43,280
my reactions should be.
Likewise, and I could have

735
00:50:43,280 --> 00:50:47,680
anticipated this, there were a
lot of questions related to what

736
00:50:47,680 --> 00:50:52,160
management style I would apply
if I had the post.

737
00:50:52,800 --> 00:50:54,920
I hadn't been talking about
management.

738
00:50:54,920 --> 00:50:59,040
I'd I wanted to do research and
do some creative teaching.

739
00:50:59,400 --> 00:51:05,840
So again, my my questions were
were very weak.

740
00:51:05,840 --> 00:51:10,840
I felt at the end of an hour
they released me to catch the

741
00:51:10,840 --> 00:51:14,680
plane back to California.
I remember my wife meeting me

742
00:51:15,240 --> 00:51:19,120
and she was quite excited.
She said, well, how was it?

743
00:51:19,120 --> 00:51:23,080
Did it did it meet your hopes?
We will we be going there?

744
00:51:24,040 --> 00:51:29,400
And I held my hand up and said
the job looked fantastic and I

745
00:51:29,400 --> 00:51:33,240
made it a real terrible job of
the interview.

746
00:51:33,720 --> 00:51:37,840
That's the end.
So I mentally got back to my

747
00:51:37,840 --> 00:51:41,840
work in Davis.
But you know, a week later the

748
00:51:41,840 --> 00:51:44,960
principal phoned again and said
the job was mine.

749
00:51:45,520 --> 00:51:50,240
It may have been a a fine
decision because usually they

750
00:51:50,240 --> 00:51:53,120
don't take that long in reaching
a decision.

751
00:51:53,480 --> 00:52:00,360
But anyway, I did accept the
position and well, by the time I

752
00:52:00,720 --> 00:52:05,800
got loose from Davis, there were
various entanglements that

753
00:52:05,800 --> 00:52:10,440
slowed my departure.
It was spring 1980.

754
00:52:10,640 --> 00:52:13,360
After I'd accepted the
appointment, the principal

755
00:52:13,360 --> 00:52:18,080
pointed out that I wouldn't be
really responsible for the

756
00:52:18,400 --> 00:52:23,000
engine testing work that my
predecessor had specialized in.

757
00:52:23,600 --> 00:52:28,320
He had a right hand man for that
work.

758
00:52:28,600 --> 00:52:33,520
And if I was agreeable, he could
be promoted to professor to thus

759
00:52:33,520 --> 00:52:35,960
removing me from any
responsibility.

760
00:52:36,120 --> 00:52:41,920
And then that's what I very much
agreed to and form my dowry

761
00:52:41,920 --> 00:52:45,680
lectureship, I recruited Michael
Leshina.

762
00:52:46,560 --> 00:52:51,000
Michael had been my final PhD
student before I left Imperial

763
00:52:51,000 --> 00:52:54,080
College.
In interim, he'd gone to work

764
00:52:54,080 --> 00:52:56,120
with Wolfgang Rodie in
Karlsruhe.

765
00:52:56,120 --> 00:53:00,760
But when I suggested that he
might rejoin me as a lecturer at

766
00:53:00,760 --> 00:53:03,160
Manchester, he was very happy to
come.

767
00:53:03,920 --> 00:53:08,480
So I was able to get off to a
very good start there because I

768
00:53:08,480 --> 00:53:13,360
could delegate to Mike
Leschziner responsibility for

769
00:53:13,800 --> 00:53:18,920
the developing software and
generally looking after the

770
00:53:18,920 --> 00:53:23,960
turbulence related work while I
got experimental work going.

771
00:53:24,880 --> 00:53:30,120
In fact, I was very lucky in
that while I was in Davis I'd

772
00:53:30,120 --> 00:53:35,200
negotiated a contract with the
Office of Naval Research, ONR as

773
00:53:35,200 --> 00:53:39,000
it's known.
The person behind that was

774
00:53:39,000 --> 00:53:44,760
someone who was very sceptical
of CFD, of what CFD codes could

775
00:53:44,760 --> 00:53:48,360
do at that time.
In particular, he was interested

776
00:53:48,520 --> 00:53:52,760
in flow through heat exchangers,
in particular, flow through a

777
00:53:52,760 --> 00:53:59,160
tube, but in a tube that went in
a series of U bends as you get

778
00:53:59,160 --> 00:54:03,080
in a heat exchanger.
He said he didn't believe that

779
00:54:03,160 --> 00:54:08,040
current CFD software could
accurately predict what heat

780
00:54:08,040 --> 00:54:11,960
transfer coefficients would
arise from the complications

781
00:54:11,960 --> 00:54:15,440
that the swirling flow that was
generated by these U bends would

782
00:54:15,440 --> 00:54:19,880
create.
Fine, I accepted that there was

783
00:54:19,880 --> 00:54:23,480
no problem transferring the
contract to Manchester.

784
00:54:24,160 --> 00:54:28,680
So we got under way and after
we'd got a very nice set of

785
00:54:29,240 --> 00:54:34,360
results, not just for a circular
U bend, circular section U bend,

786
00:54:34,360 --> 00:54:38,840
we actually also produced
experimental results for a

787
00:54:38,840 --> 00:54:42,840
square section U bend.
Real heat exchangers don't have

788
00:54:42,840 --> 00:54:48,200
a square section pipes, of
course, but it was easier to do

789
00:54:48,200 --> 00:54:53,000
the experiments using laser
Doppler anemometry going through

790
00:54:53,160 --> 00:54:56,760
a plain surface rather than a
circular surface at a time.

791
00:54:56,760 --> 00:54:59,280
It took us a little while to
work out how to do that.

792
00:55:00,160 --> 00:55:06,680
Anyway, when we went to apply
software to that we've we found

793
00:55:07,200 --> 00:55:11,000
very poor agreement.
The contract monitor was

794
00:55:11,000 --> 00:55:13,200
delighted he'd been proof
correct.

795
00:55:13,560 --> 00:55:18,120
We carried on as well as we
could refining the model.

796
00:55:18,120 --> 00:55:24,880
We found in that case that that
taking the calculation all the

797
00:55:24,880 --> 00:55:29,080
way to the wall was highly
beneficial.

798
00:55:29,240 --> 00:55:35,320
We at that point just put in the
mixing length hypothesis across

799
00:55:35,320 --> 00:55:38,120
the sub layer.
Remember this, these were

800
00:55:38,120 --> 00:55:40,720
three-dimensional flow
calculations and although

801
00:55:40,720 --> 00:55:43,960
computers were getting more and
more capable, the calculation

802
00:55:43,960 --> 00:55:49,040
like flow 3 dimensional flow
through a a succession of U

803
00:55:49,040 --> 00:55:51,480
bends stretch the resources
available.

804
00:55:51,480 --> 00:55:57,680
OK, well we then went
experimentally on to rotating U

805
00:55:57,680 --> 00:56:01,440
bends.
Now rotating U bends.

806
00:56:01,960 --> 00:56:07,280
Heat exchangers don't rotate,
but this configuration also

807
00:56:07,280 --> 00:56:13,600
arises in tubes 1 millimetre in
diameter that are inside gas

808
00:56:13,600 --> 00:56:17,920
turbine blades and because of
the pressure there and other

809
00:56:18,160 --> 00:56:21,680
other factors.
So for Rolls Royce for several

810
00:56:21,680 --> 00:56:28,880
years we continued looking at
the impact that swirl has on in

811
00:56:28,880 --> 00:56:32,800
that particular configuration.
I think on the research

812
00:56:33,240 --> 00:56:38,960
computing side rather we'd for
my money, I'd more or less run

813
00:56:38,960 --> 00:56:43,320
out of Rd.
The there didn't seem to me much

814
00:56:43,320 --> 00:56:48,160
scope within the stress
transport models or algebraic

815
00:56:48,160 --> 00:56:51,240
simplifications thereof that we
could exploit.

816
00:56:51,360 --> 00:56:55,560
And then one day in a reflective
mode, I recalled a paper that

817
00:56:55,760 --> 00:57:00,120
John Lumley had published in
1978.

818
00:57:01,160 --> 00:57:08,000
He made what I then asserted was
a absurd suggestion that

819
00:57:08,400 --> 00:57:13,080
turbulence should comply with
what he called the two component

820
00:57:13,080 --> 00:57:16,520
limit.
Turbulence, as you know, is 3

821
00:57:16,520 --> 00:57:21,600
dimensional, John said.
However, if you have a situation

822
00:57:21,600 --> 00:57:27,520
where the fluctuations just lie
in a plane, that is a state that

823
00:57:27,560 --> 00:57:31,280
you should insist on your
turbulence model agreeing with.

824
00:57:31,480 --> 00:57:35,160
Indeed, he worked out a
parameter that automatically

825
00:57:35,160 --> 00:57:39,760
went to zero whenever you did
have that two component state,

826
00:57:39,960 --> 00:57:44,000
and thus it would be a useful
parameter to use in one's

827
00:57:44,000 --> 00:57:48,360
turbulence model.
Well, in reflecting on this that

828
00:57:48,360 --> 00:57:54,760
day, I suddenly realised that as
you went closer and closer to a

829
00:57:54,760 --> 00:58:00,160
wall, the presence of the wall
damped out fluctuations normal

830
00:58:00,160 --> 00:58:04,480
to the wall, so that then as you
get close enough to the wall,

831
00:58:04,480 --> 00:58:10,680
you indeed did have turbulence
that was essentially 2

832
00:58:10,680 --> 00:58:13,600
dimensional.
At that instant I went from

833
00:58:13,600 --> 00:58:17,360
being a critic to an
enthusiastic supporter.

834
00:58:17,800 --> 00:58:21,120
It was, it really was an
overnight night thing.

835
00:58:21,120 --> 00:58:26,720
I had two other students at the
time but worked on this.

836
00:58:27,640 --> 00:58:32,520
I'm happy to mention the My name
1 was Dimitri Selikodakis and

837
00:58:32,520 --> 00:58:36,360
the other was Songfu.
Anyway, they made important

838
00:58:36,360 --> 00:58:40,640
first steps, but then their
names aren't linked with the TCL

839
00:58:40,640 --> 00:58:44,640
modelling simply because they
were in at the development stage

840
00:58:44,760 --> 00:58:51,240
at the exploiting level.
Though Li Xiaoping, another

841
00:58:51,240 --> 00:58:57,240
Chinese student who now works
for Fluent in the USA, He

842
00:58:57,240 --> 00:59:03,240
applied the scheme both to flows
along a flat plate, but also to

843
00:59:03,400 --> 00:59:06,280
riblet flows in order to reduce
the drag.

844
00:59:06,440 --> 00:59:09,680
The results from his
computations came out well.

845
00:59:09,680 --> 00:59:15,000
And then especially a little
afterwards, Tim Kraft looking at

846
00:59:15,000 --> 00:59:18,840
a whole range of turbulent flows
found that that this two

847
00:59:18,840 --> 00:59:23,320
component limit, the TCL model
as we called it, did a brilliant

848
00:59:23,320 --> 00:59:28,600
job of imitating, mimicking the
effects of buoyancy

849
00:59:28,600 --> 00:59:34,000
stratification on the behaviour
of the turbulent stresses much

850
00:59:34,000 --> 00:59:38,960
better than the other the
earlier LRR model that everyone

851
00:59:38,960 --> 00:59:42,960
still uses.
Maybe I can ask a quick

852
00:59:42,960 --> 00:59:45,720
question.
Actually on the TCL model, it

853
00:59:45,720 --> 00:59:49,760
strikes me that from my
understanding, that has probably

854
00:59:49,760 --> 00:59:53,880
the most, that was the peak of
the most sophistication, the

855
00:59:53,880 --> 00:59:57,720
most complexity in a turbans
model in, in terms of the number

856
00:59:57,720 --> 01:00:02,000
of equations, the completeness.
And yet if I look at fluent or,

857
01:00:02,000 --> 01:00:04,840
you know, other codes today,
it's probably still the case

858
01:00:04,840 --> 01:00:08,320
that people use their LR, you
know, LRR or SSG.

859
01:00:08,560 --> 01:00:11,880
Is there a reason you think that
the TCL wasn't adopted more

860
01:00:11,880 --> 01:00:14,400
wisely?
Was it just too difficult to

861
01:00:14,400 --> 01:00:15,920
implement?
Do you have any?

862
01:00:16,480 --> 01:00:20,040
Yeah, thoughts.
On that, I think it may well be

863
01:00:20,080 --> 01:00:23,280
certainly what you suggest was a
contributor.

864
01:00:23,840 --> 01:00:27,400
Maybe maybe I didn't get
involved myself in trying to

865
01:00:27,680 --> 01:00:29,680
promote the model.
I don't know.

866
01:00:29,720 --> 01:00:35,840
Dave Wilcox I think has has done
a better job in in in advocacy.

867
01:00:35,840 --> 01:00:40,640
Florian Mentor's another name
that is, is is an advocating

868
01:00:40,640 --> 01:00:42,680
that approach.
But well, I don't know.

869
01:00:43,080 --> 01:00:47,280
It's a it's a thing of history.
My philosophy is often, and I

870
01:00:47,280 --> 01:00:50,360
just wonder whether that's why
the K epsilon is still today one

871
01:00:50,360 --> 01:00:55,120
of the most widely used is there
is a simplicity is often

872
01:00:55,120 --> 01:00:58,840
preferred because it's it's
easier to implement, it's easier

873
01:00:58,840 --> 01:01:00,600
to debug, it's easier to get
right.

874
01:01:00,800 --> 01:01:04,440
And so sometimes I wonder
whether people are inherently

875
01:01:04,760 --> 01:01:08,280
favouring simpler models.
And so the K epsilon it's

876
01:01:08,360 --> 01:01:11,320
probably an easier model to
implement and test and use than

877
01:01:11,320 --> 01:01:15,480
the TCL model that is has more
places to make a mistake.

878
01:01:15,960 --> 01:01:18,280
I don't know if that's the
reason, it could be war.

879
01:01:18,960 --> 01:01:23,200
I I think as well you, you
touched on it, simplicity is a

880
01:01:23,200 --> 01:01:28,640
very key point.
But nowadays 1 is, is looking at

881
01:01:28,640 --> 01:01:34,880
a situation where computers have
developed so much that if K

882
01:01:34,880 --> 01:01:40,040
epsilon isn't good enough,
perhaps you should use a hybrid

883
01:01:40,040 --> 01:01:46,920
K epsilon LES approach.
Yeah, and LES is conceptually

884
01:01:46,920 --> 01:01:50,880
quite simple.
K epsilon is also pretty simple.

885
01:01:51,360 --> 01:01:55,360
I think people can live with
that package, maybe more easily

886
01:01:55,360 --> 01:02:00,760
than solving rather obscure
looking models for the pressure

887
01:02:00,760 --> 01:02:03,560
strain hypothesis in the in the
TC.

888
01:02:04,240 --> 01:02:08,280
Yeah, but how about, you know,
Tim Kraft, somebody who actually

889
01:02:08,280 --> 01:02:10,560
taught me when I was at
university?

890
01:02:11,680 --> 01:02:16,400
He went further, right?
You went on to move to look at

891
01:02:16,720 --> 01:02:20,760
what I would consider I guess a
blend or a theoretical blend of

892
01:02:20,760 --> 01:02:25,440
trying to bring some of the
concept of an ice to be into

893
01:02:26,120 --> 01:02:28,920
simpler models.
So this was the non linear cubic

894
01:02:28,920 --> 01:02:31,600
models, right?
That was this the next stage, I

895
01:02:31,600 --> 01:02:33,160
guess, of the turbans modelling
work.

896
01:02:33,800 --> 01:02:38,080
Very much so.
Toyota had contacted me wanting

897
01:02:38,080 --> 01:02:43,280
to send one of their staff at
the time, Kazuyi Kosuga, to work

898
01:02:43,280 --> 01:02:47,000
on me and I've I'd figured that
they wouldn't be interested in

899
01:02:47,000 --> 01:02:49,760
TCL modelling.
It really would be a step too

900
01:02:49,760 --> 01:02:54,860
far for this car manufacturer.
But we did agree to look at non

901
01:02:54,860 --> 01:02:59,680
linear Eddy viscosity models.
There had already been half a

902
01:02:59,680 --> 01:03:05,760
dozen schemes that brought in
quadratic terms in addition to

903
01:03:05,760 --> 01:03:09,680
the principal linear term of an
Eddy viscosity model.

904
01:03:09,760 --> 01:03:15,680
We started off looking at those
five schemes that already come

905
01:03:15,680 --> 01:03:21,280
forward and what we concluded
was that because these five

906
01:03:21,280 --> 01:03:25,480
models were also very different,
different magnitudes of

907
01:03:25,480 --> 01:03:29,520
coefficients for different
terms, these models had been

908
01:03:29,520 --> 01:03:33,800
designed so that they cope with
one particular class of flow

909
01:03:33,800 --> 01:03:37,240
that a linearity viscosity model
didn't get right.

910
01:03:37,320 --> 01:03:42,080
We concluded that since the
models weren't anything like the

911
01:03:42,080 --> 01:03:47,240
same, we would be wasting our
time to continue research at the

912
01:03:47,960 --> 01:03:51,840
quadratic level.
So for the first time then, we

913
01:03:52,160 --> 01:03:55,400
we explored modelling at cubic
level.

914
01:03:55,960 --> 01:04:00,600
Cubic level of course brought in
many more potential terms, each

915
01:04:00,600 --> 01:04:02,760
with empirical coefficients to
tune.

916
01:04:03,240 --> 01:04:09,400
But Kazuhikosuga very patiently
and very thoroughly looked at a

917
01:04:09,400 --> 01:04:13,960
whole wide range of flows that
were difficult or couldn't be

918
01:04:13,960 --> 01:04:19,720
predicted with a linear Eddy
viscosity model, and we ended up

919
01:04:19,720 --> 01:04:26,240
with a version that perhaps
wasn't the final word in cubic

920
01:04:26,360 --> 01:04:30,840
Eddy viscosity modelling at at
least did a hell of a lot better

921
01:04:31,200 --> 01:04:37,280
for a large number of flows than
than the quadratic models.

922
01:04:38,320 --> 01:04:42,920
So he was content.
I'd say after returning to

923
01:04:43,240 --> 01:04:46,560
Japan, he worked for a few years
with Toyota.

924
01:04:46,560 --> 01:04:52,600
But then this is interesting.
He got permission from Toyota to

925
01:04:52,600 --> 01:04:56,080
move to a university position.
Oh nice.

926
01:04:56,920 --> 01:05:01,240
You could you could see that as,
as you've just said Neil, a

927
01:05:01,240 --> 01:05:06,920
simplification from from the
pinnacle of TCL modelling.

928
01:05:07,280 --> 01:05:12,400
And I guess the next step I took
in research went a step further.

929
01:05:12,760 --> 01:05:19,400
What really bugged me was that
still in commercial CFD, people

930
01:05:20,000 --> 01:05:27,040
so frequently use wall functions
based on this old idea and very

931
01:05:27,040 --> 01:05:32,680
limited, a very limited idea
that the near wall velocity

932
01:05:32,680 --> 01:05:35,600
profile was universal.
What could we do with that?

933
01:05:35,760 --> 01:05:40,240
Well, I worked on this with Tim
Craft, who had become a lecturer

934
01:05:40,240 --> 01:05:44,520
at the time, and Hector
Yaccapedes, an earlier student

935
01:05:44,520 --> 01:05:48,720
that had worked on flow around
Benz with me, who was now a

936
01:05:48,720 --> 01:05:52,840
professor.
In fact, we decided we'd figure

937
01:05:52,840 --> 01:05:56,840
out a better way of building a
wall function.

938
01:05:57,320 --> 01:06:02,480
Indeed, we worked on 2 schemes.
There was a analytical approach.

939
01:06:02,480 --> 01:06:08,280
We took the view that although
the near wall velocity profile

940
01:06:08,560 --> 01:06:14,040
wasn't universal in most of the
flows that one would want to

941
01:06:14,040 --> 01:06:19,880
look at, maybe the turbulent
Eddy viscosity would be much

942
01:06:19,880 --> 01:06:23,760
more nearly universal,
Particularly as we agreed to

943
01:06:23,760 --> 01:06:28,960
allow the viscous sub layer
where there was 0 turbulent

944
01:06:28,960 --> 01:06:31,400
mixing.
According to our model, we could

945
01:06:31,400 --> 01:06:36,520
vary that in thickness depending
upon the gradient of shear

946
01:06:36,520 --> 01:06:42,640
stress across the layer.
Well, this we worked on with a

947
01:06:42,640 --> 01:06:46,160
Russian student.
My only Russian student, Alexi

948
01:06:46,160 --> 01:06:51,120
Gorasimov, was just fun to work
with and I'm glad to say that

949
01:06:51,160 --> 01:06:56,520
the model he came up with, what
was called the analytical wall

950
01:06:56,520 --> 01:07:01,560
function, did pretty well.
It's widely used at Manchester

951
01:07:01,560 --> 01:07:06,120
now and and is at least
incorporated in some of the

952
01:07:06,120 --> 01:07:10,960
commercial software.
It's a lot, lot better than log

953
01:07:10,960 --> 01:07:16,760
roll wall functions.
They should be made illegal, but

954
01:07:16,760 --> 01:07:21,560
we also developed a second
scheme in situations where you

955
01:07:21,560 --> 01:07:25,640
have the velocity vector
changing direction across the

956
01:07:25,640 --> 01:07:30,160
viscous layer, such as a rises
in those flow around U bends,

957
01:07:30,160 --> 01:07:33,560
very tight U bends.
We developed a numerical scheme.

958
01:07:33,560 --> 01:07:38,680
I I won't attempt to go into any
detail on that, but the key

959
01:07:38,680 --> 01:07:43,400
thing was that just as in a
boundary layer solver, if you

960
01:07:43,400 --> 01:07:48,920
think of a but 2D boundary layer
solver, you treat the static

961
01:07:48,920 --> 01:07:52,880
pressure as though it is uniform
across the layer.

962
01:07:53,000 --> 01:07:58,240
We applied the same slight
approximation, but only to the

963
01:07:58,840 --> 01:08:02,040
very near wall region covered by
the wall function.

964
01:08:02,040 --> 01:08:07,800
And I won't go into the details.
Indeed I've forgotten some of

965
01:08:07,800 --> 01:08:10,320
the details by now.
It's a while ago.

966
01:08:10,320 --> 01:08:16,200
But that permitted us to very
much reduce the cost of using

967
01:08:16,200 --> 01:08:19,600
quite advanced models.
I mean, Bill Jones's Paul

968
01:08:19,600 --> 01:08:24,520
Reynolds number model could be
put in or or any any other other

969
01:08:24,520 --> 01:08:28,680
model and it reduced the
computing time by something

970
01:08:28,680 --> 01:08:34,080
between 80% and 90%.
So it represents a huge saving.

971
01:08:34,359 --> 01:08:38,120
I should just maybe add a point
and maybe you're not even aware

972
01:08:38,120 --> 01:08:42,640
of this, that I have seen a
resurgence of the interest in

973
01:08:42,640 --> 01:08:47,439
the work that you did with Tim
and Hector for advanced war

974
01:08:47,439 --> 01:08:50,680
functions in the context
actually of LES.

975
01:08:51,399 --> 01:08:54,920
That now because there is a
resurgence of interest in the

976
01:08:54,920 --> 01:09:01,439
war modelled LES, there is a
realization that the model used

977
01:09:01,960 --> 01:09:04,000
to approximate the near war
behaviour.

978
01:09:04,600 --> 01:09:08,600
Can we look at more advanced
ways of calculating that?

979
01:09:08,600 --> 01:09:12,000
And I I've seen now people
reference and look at that work

980
01:09:12,880 --> 01:09:15,560
not in the context of Rams, but
actually in the context of LES,

981
01:09:15,560 --> 01:09:17,840
which I thought is quite
interesting how work that was

982
01:09:17,840 --> 01:09:22,720
done, you know, 30 years ago is
now being re looked at in a in a

983
01:09:22,720 --> 01:09:24,920
different context, but still.
Yeah.

984
01:09:25,279 --> 01:09:27,960
So anyway, just a.
Thank you Neil.

985
01:09:27,960 --> 01:09:31,200
I, I was not aware of this
resurgence of interest.

986
01:09:31,200 --> 01:09:37,640
Long may it continue, but I, I
have to say that that having got

987
01:09:37,640 --> 01:09:44,520
that far, what I found was that
turbulence models was looked on

988
01:09:44,560 --> 01:09:47,319
as what might be called a mature
subject.

989
01:09:48,000 --> 01:09:52,080
People weren't interested in
looking for radical changes in

990
01:09:52,080 --> 01:09:55,400
in modelling.
It was applications that were

991
01:09:55,400 --> 01:09:59,240
very much to the flock for I
didn't feel that that was what I

992
01:09:59,240 --> 01:10:06,320
was perhaps best at at doing,
though I, I did, I did supervise

993
01:10:06,320 --> 01:10:11,800
one PhD student by a friend of
yours, Alistair, and that was

994
01:10:11,800 --> 01:10:14,280
very successful.
He was looking at in nine tube

995
01:10:14,280 --> 01:10:16,760
banks and it was quite
extraordinary.

996
01:10:16,760 --> 01:10:22,440
We found the the sorts of
deviations from from going

997
01:10:22,440 --> 01:10:28,360
straight through of N92 bank
heat exchanger tended to develop

998
01:10:28,880 --> 01:10:33,320
a diagonal path through that.
I should maybe just interrupt

999
01:10:33,320 --> 01:10:35,440
you slightly.
I, I was mean to say it before,

1000
01:10:35,440 --> 01:10:38,960
but maybe this is a good time to
say it that almost as a, an

1001
01:10:38,960 --> 01:10:42,480
observation or to people
listening that I studied at

1002
01:10:42,480 --> 01:10:45,040
Manchester University with
Alistair as well.

1003
01:10:45,120 --> 01:10:49,000
And we did our undergraduate
PhDs and, and you taught us and

1004
01:10:49,000 --> 01:10:52,040
so did Tim craft and so did
hectic Yakovides and these folk.

1005
01:10:52,040 --> 01:10:57,120
Not Michael, I guess Michael, I
think moved to Imperial then and

1006
01:10:57,840 --> 01:11:01,560
but we didn't know who you were.
We didn't know who Tim was.

1007
01:11:01,560 --> 01:11:04,280
We didn't know.
And I, I know Alastair and I

1008
01:11:04,280 --> 01:11:06,600
talk about this now that we feel
bad in a way.

1009
01:11:06,600 --> 01:11:07,880
And I'm sure others are like
that.

1010
01:11:07,880 --> 01:11:10,520
They see some professor come in,
teach a subject, second year

1011
01:11:10,520 --> 01:11:13,320
something and you all, you don't
mean to be disrespectful, but

1012
01:11:13,680 --> 01:11:15,000
you know, you don't know who
they are.

1013
01:11:15,000 --> 01:11:18,200
And it's only later you look
back and think, oh wow, I was,

1014
01:11:18,240 --> 01:11:21,240
you know, taught by this person
or supervised.

1015
01:11:21,240 --> 01:11:25,760
And I, I wonder, I think you
mentioned to me this happens

1016
01:11:25,760 --> 01:11:28,800
sometimes that people come or
want to take a selfie with you

1017
01:11:28,800 --> 01:11:31,880
or something.
Because now with social media, I

1018
01:11:31,880 --> 01:11:33,960
guess people know who people are
more.

1019
01:11:33,960 --> 01:11:36,680
But at the time we had no clue.
And it was an honour to be

1020
01:11:36,680 --> 01:11:38,720
taught by you.
But I feel guilty that we didn't

1021
01:11:38,720 --> 01:11:42,480
say it at the time.
Well, I have no thoughts on

1022
01:11:42,480 --> 01:11:44,360
that.
Indeed you mentioned people

1023
01:11:44,360 --> 01:11:46,240
coming in to have selfies with
me.

1024
01:11:46,480 --> 01:11:50,200
I I was just amazed and thought
they were slightly crazy but

1025
01:11:50,920 --> 01:11:55,560
complied with their request to
to be photographed.

1026
01:11:56,600 --> 01:12:01,880
Well, I suppose the one of the
reasons that slightly steered me

1027
01:12:01,880 --> 01:12:08,440
away from continuing too deeply
in basically CFD applications.

1028
01:12:08,440 --> 01:12:12,440
Much as there were very
interesting things to explore, I

1029
01:12:12,840 --> 01:12:16,680
would in fact mention another
application case.

1030
01:12:16,680 --> 01:12:21,120
We were looking at trailing
vortices behind a wing.

1031
01:12:21,680 --> 01:12:24,880
There was a good set of
experimental data, and we

1032
01:12:24,880 --> 01:12:30,000
computed that with a Eddy
viscosity model, and as we knew

1033
01:12:30,000 --> 01:12:33,880
it would, the swirl died out far
too quickly.

1034
01:12:34,320 --> 01:12:38,440
Now the trailing vortices behind
a wing in practice are known to

1035
01:12:38,440 --> 01:12:42,760
persist a long time, so that a
big aircraft landing at an

1036
01:12:42,760 --> 01:12:48,480
airport would make it really
dangerous for a plane coming in

1037
01:12:48,640 --> 01:12:53,080
a minute or so after them on the
same track because the swirl

1038
01:12:53,080 --> 01:12:59,000
persisted and persisted.
The Eddie Viscosity model said

1039
01:12:59,000 --> 01:13:02,480
don't worry folks, the swirl
dies out very quickly.

1040
01:13:02,480 --> 01:13:06,560
But experiments that Peter
Bradshaw had done said, no, it

1041
01:13:06,560 --> 01:13:09,280
doesn't die out.
It hangs around an awful long

1042
01:13:09,280 --> 01:13:12,560
time.
And I'm happy to say that one of

1043
01:13:12,560 --> 01:13:19,080
the applications that I did with
Tim Craft at Manchester was to

1044
01:13:19,080 --> 01:13:23,680
look at this with the TCL model.
And the TCL model was the only

1045
01:13:23,680 --> 01:13:27,800
one of four schemes that we
looked at that in any way

1046
01:13:27,800 --> 01:13:31,320
mimicked the observed
experimental behavior.

1047
01:13:31,440 --> 01:13:35,320
I will just add if you don't
mind a quick again interesting

1048
01:13:35,320 --> 01:13:37,560
thing that you may or may not be
aware of and it's probably one

1049
01:13:37,560 --> 01:13:40,360
of the reasons that Alistair
works where he does now at the

1050
01:13:40,360 --> 01:13:44,400
Formula One team, is that use
case of RANS turbans modelling

1051
01:13:44,440 --> 01:13:48,160
for highly vortex driven flows
is a key use case in Formula

1052
01:13:48,160 --> 01:13:51,320
One.
And actually from when I was

1053
01:13:51,320 --> 01:13:54,700
working and even recently, I
still see people looking at non

1054
01:13:54,700 --> 01:13:58,840
linearity viscosity models and
all stress models because the

1055
01:13:58,840 --> 01:14:03,120
flow around a Formula One chi is
driven by 10s or more of

1056
01:14:03,120 --> 01:14:06,940
individual vortices and they
find that they need these non

1057
01:14:06,940 --> 01:14:10,240
linear terms to capture it more
nicely.

1058
01:14:10,240 --> 01:14:14,360
So even today, I think that's
one of the industries that still

1059
01:14:14,360 --> 01:14:16,640
are very much indeterminate
modelling.

1060
01:14:16,640 --> 01:14:21,000
So yeah, yeah, that's that, that
wing tip exact test case I've

1061
01:14:21,000 --> 01:14:24,680
seen used internally at in F1
teams to investigate different

1062
01:14:24,680 --> 01:14:25,760
terms models.
So.

1063
01:14:26,520 --> 01:14:29,240
Gosh.
Well, thank you.

1064
01:14:29,440 --> 01:14:34,120
I hadn't supposed that that
ground based object like a

1065
01:14:34,120 --> 01:14:37,680
racing car would encounter the
same problems.

1066
01:14:38,480 --> 01:14:42,440
Yeah, that's because all the
wings, they generate the tips

1067
01:14:42,480 --> 01:14:44,480
and there's so many of those
individual wings, there's,

1068
01:14:44,880 --> 01:14:49,240
there's probably 40 different
vortices I guess on the car all

1069
01:14:49,240 --> 01:14:51,240
touching each other.
You need a pretty fine.

1070
01:14:51,480 --> 01:14:53,560
It's a result, yes.
Well, yeah, there's like a

1071
01:14:53,560 --> 01:14:56,360
billion grid points nowadays, so
things have moved on.

1072
01:14:56,360 --> 01:14:58,640
But yes, sorry I interrupted
you.

1073
01:14:58,640 --> 01:15:02,800
I think you were talking more
about the Osborne Reynolds and

1074
01:15:02,800 --> 01:15:05,600
and some of that work.
Yeah, well, I've really reached

1075
01:15:05,600 --> 01:15:09,280
the end of the end of the line.
I thought I was also getting a

1076
01:15:09,280 --> 01:15:14,600
bit old and so I was interested
that the Royal Society announced

1077
01:15:14,960 --> 01:15:20,920
that they had the original
copies of referees reports from

1078
01:15:20,920 --> 01:15:24,440
some of the early papers.
Now I was quite interested in

1079
01:15:24,440 --> 01:15:27,680
Osborne Reynolds, of course.
He'd been a professor at

1080
01:15:27,680 --> 01:15:31,880
Manchester, forerunner of
Manchester University, but also

1081
01:15:31,880 --> 01:15:34,880
he his paper on Reynolds
averaging.

1082
01:15:34,880 --> 01:15:39,520
Whilst it didn't actually get
into the problems of modelling

1083
01:15:39,520 --> 01:15:43,560
the Reynolds stresses, at least
it marked a starting point for

1084
01:15:43,560 --> 01:15:46,840
the subject that I'd been
involved in for most of my

1085
01:15:46,840 --> 01:15:49,920
professional career.
So he asked whether they had

1086
01:15:49,920 --> 01:15:56,000
copies of Reynolds papers.
Judy travelled down to London to

1087
01:15:56,440 --> 01:16:01,920
see them.
And again was I was just blown

1088
01:16:01,920 --> 01:16:04,760
away.
I was blown away in much the

1089
01:16:04,760 --> 01:16:09,200
same way that first coming to
you Miss had had done for me.

1090
01:16:09,560 --> 01:16:17,280
You got communications from
Horace Lamb, George Stokes, from

1091
01:16:17,280 --> 01:16:21,600
Reynolds of course, really from
from all of these people that

1092
01:16:21,600 --> 01:16:26,480
were involved in refereeing or
acting as editor of of the

1093
01:16:26,560 --> 01:16:29,520
manuscripts that Reynolds had
submitted.

1094
01:16:29,520 --> 01:16:34,960
So I said, well, can I have a
copy of these?

1095
01:16:35,240 --> 01:16:38,360
Yes.
The Royal Society said no, I

1096
01:16:38,360 --> 01:16:41,520
could not Xerox them.
They wouldn't allow me to Xerox

1097
01:16:41,520 --> 01:16:46,520
them, but they could arrange for
their photographer to come in

1098
01:16:46,520 --> 01:16:50,000
and copy them for me, which they
duly did.

1099
01:16:50,120 --> 01:16:56,240
I was charged 75 lbs for the
privilege which I the other day

1100
01:16:56,240 --> 01:16:58,400
I looked up as to what that
would be today.

1101
01:16:58,400 --> 01:17:03,600
It was a little over £200 but I
happily paid that in order to

1102
01:17:03,640 --> 01:17:08,440
get get the photographs and
subsequently then I wrote a

1103
01:17:08,720 --> 01:17:16,080
paper on how despite crushing
referees reports, nevertheless

1104
01:17:16,080 --> 01:17:21,080
Osborne Reynolds did publish his
paper on Reynolds averaging.

1105
01:17:21,680 --> 01:17:26,680
Well that's a lesson on even the
famous and well known people

1106
01:17:26,680 --> 01:17:30,200
like Osborne Reynolds can get
very harsh reviews, so maybe

1107
01:17:30,200 --> 01:17:34,440
that's reassuring for everybody
else who probably also has had

1108
01:17:34,440 --> 01:17:37,000
those.
I'm sure it wouldn't have been

1109
01:17:37,000 --> 01:17:41,920
published except that the
earlier paper that he'd

1110
01:17:42,160 --> 01:17:46,840
published in which he discovered
that transition occurred at a

1111
01:17:46,840 --> 01:17:50,320
particular of what we call today
a particular critical Reynolds

1112
01:17:50,320 --> 01:17:51,920
number.
If he hadn't published that

1113
01:17:51,920 --> 01:17:56,560
experimental paper first because
the referees were saying things

1114
01:17:56,560 --> 01:17:59,640
like the previous work he did
was very good.

1115
01:17:59,640 --> 01:18:03,960
Maybe there's something in this,
but I can't see it that that was

1116
01:18:03,960 --> 01:18:06,160
probably the reason it got
published.

1117
01:18:06,400 --> 01:18:10,200
Of course, having having
published one paper, you get a

1118
01:18:10,200 --> 01:18:15,560
request from conference
organiser, could I give a paper

1119
01:18:15,560 --> 01:18:21,320
just like that one?
And of course my response is I

1120
01:18:21,320 --> 01:18:24,520
couldn't bear to give the same
paper twice.

1121
01:18:24,520 --> 01:18:29,640
But what I discovered was that
at Manchester they had all of

1122
01:18:29,640 --> 01:18:34,080
the archive material from
Reynolds applying for a his

1123
01:18:34,080 --> 01:18:36,480
chair.
Retired colleague of mine had

1124
01:18:36,480 --> 01:18:40,320
also been following up on
Reynolds's life, a person called

1125
01:18:40,320 --> 01:18:44,960
Derek Jackson.
And so we collaborated in

1126
01:18:45,080 --> 01:18:51,600
producing a much fuller paper on
Reynolds's life as a whole that

1127
01:18:52,080 --> 01:18:54,960
was was published in a book that
I forget.

1128
01:18:54,960 --> 01:18:56,800
Let me find the name of the book
here.

1129
01:18:56,800 --> 01:19:00,440
It is A Voyage Through
Turbulence that was edited by

1130
01:19:00,440 --> 01:19:03,000
Keith Moffat and others from
Cambridge.

1131
01:19:03,120 --> 01:19:07,520
Anyway, I don't know whether it
was connected with these papers

1132
01:19:07,520 --> 01:19:10,960
when colleagues in the Royal
Society died.

1133
01:19:11,040 --> 01:19:17,360
It's the practice of the Royal
Society to produce a 25 or 30

1134
01:19:17,360 --> 01:19:21,040
page memoir on their lives,
their achievements.

1135
01:19:21,520 --> 01:19:28,080
So I was when my friend Jim
Whitelaw passed away, I was

1136
01:19:28,080 --> 01:19:32,000
asked to write his.
And you know, that is, that is

1137
01:19:32,000 --> 01:19:36,120
really an interesting branch of
research that was quite like

1138
01:19:36,120 --> 01:19:42,040
looking at looking at Osborne
Reynolds's past life because Jim

1139
01:19:42,040 --> 01:19:45,760
had produced a huge catalog of
what he'd done.

1140
01:19:45,760 --> 01:19:50,200
And so as a matter of sifting
through that, pulling out the

1141
01:19:50,200 --> 01:19:53,160
aspects that would be
particularly important to

1142
01:19:53,160 --> 01:19:56,640
stress, plus any personal views
I might have.

1143
01:19:57,080 --> 01:20:00,400
So that started following Bron
Spaulding's death.

1144
01:20:00,440 --> 01:20:05,000
I I also.
Contributed to his memoir and

1145
01:20:05,000 --> 01:20:09,000
now most recently, Peter
Bradshaw, who died last year.

1146
01:20:09,520 --> 01:20:15,120
I've written his article.
So life in my retirement hasn't,

1147
01:20:15,360 --> 01:20:20,000
hasn't by any means been without
involvement with turbulence.

1148
01:20:21,040 --> 01:20:25,280
Bryant Spalding, When we started
off in the earlier discussions

1149
01:20:25,280 --> 01:20:29,520
about the beginning of your
career, you had the initial chat

1150
01:20:29,520 --> 01:20:34,000
about where to study, then the
offer of coming back to Imperial

1151
01:20:34,160 --> 01:20:38,040
and obviously then there was a a
sort of falling out and then

1152
01:20:38,040 --> 01:20:42,240
leaving to UC Davis.
What was your relationship like

1153
01:20:42,480 --> 01:20:45,480
later on in in your career?
Did you stay in touch?

1154
01:20:45,480 --> 01:20:48,480
Did you?
Yeah.

1155
01:20:48,480 --> 01:20:52,040
How was your relationship when
you came back to you missed?

1156
01:20:52,400 --> 01:20:55,640
Well, when I came back to you
missed it was.

1157
01:20:55,880 --> 01:20:59,880
It was static.
Nothing had moved by then, but

1158
01:20:59,880 --> 01:21:07,200
then when in 1994 received a
note notice that I was to be

1159
01:21:07,200 --> 01:21:12,880
admitted to the Royal Society, I
got a warm, very brief but brief

1160
01:21:12,880 --> 01:21:15,280
brevity is certainly sporting
style.

1161
01:21:15,640 --> 01:21:20,640
A brief note congratulating me.
I didn't respond to that.

1162
01:21:20,640 --> 01:21:23,720
I think in as generous a way as
I could.

1163
01:21:23,720 --> 01:21:29,920
We, we might have developed much
closer linkages again when he

1164
01:21:29,920 --> 01:21:34,640
was when he was reaching his
90th birthday, there was a, a

1165
01:21:34,640 --> 01:21:39,200
celebration for him and I, I was
distantly involved in helping to

1166
01:21:39,200 --> 01:21:43,320
organize that.
And of course we met there and

1167
01:21:43,600 --> 01:21:46,560
exchanged pleasantries between
us.

1168
01:21:46,560 --> 01:21:50,120
I I guess there was still
slightly a feeling of the

1169
01:21:50,120 --> 01:21:52,600
tension.
I think the last time I saw him

1170
01:21:52,960 --> 01:21:57,520
was when I was giving, We were
both giving, in fact invited

1171
01:21:57,520 --> 01:22:00,200
lectures at a meeting in
Sarajevo.

1172
01:22:00,200 --> 01:22:05,040
I would by then had worked into
the area of climate change and

1173
01:22:05,360 --> 01:22:09,560
that was the topic of my
lecture, really suggesting how

1174
01:22:09,560 --> 01:22:14,880
engineers with their experience
and now of being able to predict

1175
01:22:15,640 --> 01:22:20,040
turbulent swirling flows could
actually contribute to the

1176
01:22:20,040 --> 01:22:25,920
modelling of hurricanes, perhaps
devising methods to diminish the

1177
01:22:25,920 --> 01:22:31,400
intensity of a hurricane.
I think the paper went over the

1178
01:22:31,400 --> 01:22:36,560
heads of those there.
There was, I think, no question

1179
01:22:36,560 --> 01:22:41,120
at all from the floor except
from Brian Spalding.

1180
01:22:41,120 --> 01:22:44,160
He was sad in the front row of
the audience.

1181
01:22:44,400 --> 01:22:47,320
We did mend our defences between
us.

1182
01:22:47,640 --> 01:22:52,200
I didn't do as much as I should
have done, and I'm sorry, but I

1183
01:22:52,200 --> 01:22:56,800
hope in contributing to his bio
memoir, I'm forgiven.

1184
01:22:59,200 --> 01:23:04,360
My other question, I'm kind of
see how you saw it from the

1185
01:23:04,440 --> 01:23:09,240
outside.
Often the turbulent modelling,

1186
01:23:09,240 --> 01:23:12,640
particularly in a Rands context,
it's often seen as a almost a

1187
01:23:12,640 --> 01:23:19,120
competition between Philippe's
Ballade, you know, Florio Mentor

1188
01:23:19,360 --> 01:23:23,320
yourself, Wilcox, how much did
you see it that way in the

1189
01:23:23,320 --> 01:23:25,000
night?
And I guess you had done it a

1190
01:23:25,000 --> 01:23:28,920
little bit before, but in the
Seventies, 80s and 90s, were you

1191
01:23:28,920 --> 01:23:33,200
aware of this almost papers
always comparing the different

1192
01:23:33,200 --> 01:23:35,920
turbans modelling approaches and
which one was better?

1193
01:23:35,920 --> 01:23:39,960
Was that something you aware of
or was it not?

1194
01:23:40,520 --> 01:23:44,680
Yeah, part of your thinking.
I guess one could say I was

1195
01:23:44,840 --> 01:23:50,400
dimly aware of, but I was so
interested, you might say

1196
01:23:50,400 --> 01:23:56,480
obsessed with tackling the
problems in research that I felt

1197
01:23:56,480 --> 01:24:01,480
I needed to deal with.
I I wasn't looking over my

1198
01:24:01,480 --> 01:24:05,640
shoulder all the time.
Looking over one shoulder in

1199
01:24:05,640 --> 01:24:09,120
implies people are behind me.
Maybe some some of.

1200
01:24:09,480 --> 01:24:13,240
Do you think it's ultimately
though, just a matter of where

1201
01:24:13,240 --> 01:24:18,080
you studied and what your
funding was, new use cases, If

1202
01:24:18,080 --> 01:24:22,960
you're in at Stanford and you're
in the US, you have close links

1203
01:24:22,960 --> 01:24:26,000
with NASA and the aerospace
industry, you're going to be

1204
01:24:26,000 --> 01:24:29,520
solving airplane cases.
And so I wonder whether that

1205
01:24:29,520 --> 01:24:31,640
motivated the Sparta, Maris and
those.

1206
01:24:31,640 --> 01:24:37,600
And if you had, instead of being
funded by, you know, Boeing or

1207
01:24:37,600 --> 01:24:41,720
or Rolls Royce, sorry, or
Airbus, or would you have

1208
01:24:41,720 --> 01:24:45,360
naturally pivoted and maybe come
up with a slightly different

1209
01:24:45,360 --> 01:24:49,120
terms model?
Is it ultimately that you were

1210
01:24:49,120 --> 01:24:51,560
driven a little bit by the
problems you were trying to

1211
01:24:51,560 --> 01:24:52,720
solve?
I haven't.

1212
01:24:53,280 --> 01:24:56,920
I haven't really thought of it
that way, but I think I think

1213
01:24:56,920 --> 01:25:00,440
that's it's correct.
Had I, had I been at Stanford,

1214
01:25:00,440 --> 01:25:06,440
say yes, NASA Ames would be the
natural point of collaboration

1215
01:25:06,760 --> 01:25:08,760
in research.
Who knows?

1216
01:25:08,880 --> 01:25:12,520
I don't.
Well, I I say, I don't think I

1217
01:25:12,520 --> 01:25:17,080
would have gone for A1 equation
model as Philippe Spella.

1218
01:25:17,640 --> 01:25:19,480
Yeah.
And it's interesting, I think

1219
01:25:19,480 --> 01:25:22,600
now if you look, even with the
Spallitomaris, there's a lot of

1220
01:25:22,600 --> 01:25:26,800
modifications to try and add
some of these non linear terms.

1221
01:25:26,800 --> 01:25:31,080
So I, I think ultimately people
come from different directions

1222
01:25:31,080 --> 01:25:33,400
and you know, I guess you can
argue which one's correct and

1223
01:25:33,400 --> 01:25:36,120
which one's not.
But yeah, it, it's just a

1224
01:25:36,120 --> 01:25:39,680
curiosity to us externally,
because if you open up antis

1225
01:25:39,680 --> 01:25:44,000
Fluent or Star CCM or one of
these commercial packages, you

1226
01:25:44,000 --> 01:25:47,200
are almost, you know, this, I
didn't tell you, but you have

1227
01:25:47,200 --> 01:25:50,120
radio buttons on which turbans
model to pick.

1228
01:25:50,440 --> 01:25:52,840
Do I pick the K silent?
Do I pick the K Omega?

1229
01:25:53,280 --> 01:25:56,440
And in some ways, if you have no
context of the background, it is

1230
01:25:56,440 --> 01:25:58,360
in some ways just which one do
you pick?

1231
01:25:58,520 --> 01:26:01,400
And that's why people often find
it so interesting that there's

1232
01:26:01,400 --> 01:26:05,320
these different options and how
did they come about and what was

1233
01:26:05,320 --> 01:26:07,560
their motivation.
So that ends the question.

1234
01:26:07,640 --> 01:26:13,480
So maybe to finish off, what if
you were to now, you know,

1235
01:26:13,480 --> 01:26:16,560
you're speaking to your 20 year
old self, what advice would you

1236
01:26:16,560 --> 01:26:19,280
give having all of what you've
learned through your amazing

1237
01:26:19,280 --> 01:26:20,400
career?
What?

1238
01:26:20,400 --> 01:26:22,480
What words of wisdom would you
impart?

1239
01:26:22,640 --> 01:26:26,560
Gosh, it's hard to imagine a 20
year old who would sit and

1240
01:26:28,320 --> 01:26:33,920
listen to somebody closer to 90
than 80I.

1241
01:26:34,080 --> 01:26:38,320
I suppose looking back over my
life, what I can see is that

1242
01:26:38,720 --> 01:26:43,560
changes have come about.
Really not of my own driving,

1243
01:26:43,920 --> 01:26:47,440
but I've somehow been thrust
upon me.

1244
01:26:47,440 --> 01:26:53,320
And I think I would say that
people should be ready to accept

1245
01:26:53,320 --> 01:26:58,720
change, not be downcast by it
nor overly ill related, but to

1246
01:26:58,720 --> 01:27:04,640
be inquisitive of of change.
And I think making changes

1247
01:27:04,960 --> 01:27:10,080
constructively has, in a sense,
reflects my approach to

1248
01:27:10,080 --> 01:27:13,360
modelling.
When we'd reached the stage

1249
01:27:13,560 --> 01:27:17,600
where it was just a matter of
pushing a button to, as you had

1250
01:27:17,640 --> 01:27:22,400
alluded to, to choose which
model is applicable, that's when

1251
01:27:22,400 --> 01:27:27,080
I think it's time for me to say
thanks but no thanks, I'll do

1252
01:27:27,160 --> 01:27:32,000
something else.
Great words of wisdom and thank

1253
01:27:32,000 --> 01:27:34,880
you so much for sharing your
stories and your work.

1254
01:27:35,040 --> 01:27:40,200
I'm sure I speak for everybody
to say that the impact of, you

1255
01:27:40,200 --> 01:27:44,840
know, the K Epsilon, the LLR and
the wolf function work is today

1256
01:27:44,840 --> 01:27:48,760
used by hundreds of thousands of
engineers across the globe to

1257
01:27:48,760 --> 01:27:52,120
design the things that we and
you, the listener use it every

1258
01:27:52,120 --> 01:27:54,080
day.
So the impact, even though some

1259
01:27:54,080 --> 01:27:57,760
of that work was 50 years ago,
it is still impacting today,

1260
01:27:57,760 --> 01:28:00,960
which is I think an incredible
testament to the work you've

1261
01:28:00,960 --> 01:28:03,320
done.
So thank you for being on today

1262
01:28:03,320 --> 01:28:04,400
and it was great to speak to
you.

1263
01:28:04,840 --> 01:28:07,000
Well, thank you, Neil.
It's been fun.

1264
01:28:07,840 --> 01:28:08,240
Bye bye.