Hi, thank you both for your reply. Indeed, I would like to incorporate the non-Newtonian property of blood while using a turbulence model. The non-Newtonian property shows that viscosity should decrease with higher shear rate, so a lower viscosity with higher presence of turbulence? I was thinking about incorporating compressibity, as the red blood cells introduce this property of blood, slightly, but it's neglectable in most cases. I will ignore it in my case. 

I'm simulating the filling phase of the left ventricle in which turbulence is present. I tried using a laminar model but the residuals did not converge (steady state simulation). Also from literature I see that the SST k-omega model seems to be applicable for this case.

So I want to introduce the non-newtonian blood property for an SST k-omega model, maybe with the non-newtonian power law model? But this is disable for the SST k-omega model. Why is this normally disabled? (is it incorrect to model fluid as non-newtonian for the turbulence model?)