Compared to the aerospace and automotive sector, bio-engineering is far less than mature in the use of CFD. This is however a very interesting field - to see how CFD methods can help the medical profession to better understand the flow of blood inside the body or how our respiratory systems works. There are many many applications where could potentially be useful.
One example application, as shown in the paper below, is whether CFD can be used to assess whether an aneurysm will rupture and thus needs surgery. We can use CFD to predict the blood flow and see where there are areas of low wall-shear stress which indicate points of potential rupture. This could help doctors to better decide who needs treatment, potentially saving lives.Berg et al. - 2015 - The Computational Fluid Dynamics Rupture Challenge 2013-Phase II Variability of Hemodynamic Simulations in Two Intr