I would advice not to use RANS formulation for this case! The small lenght scale could allow you to use LES/DNS to predict if you have transition. But I would advice also to use a non-newtonian fluid model.

I think you should use FSI to survey the transition and trace the flow behavior (viscosity model for blood maybe Cason model).

Dear Filippo Maria Denaro

I am using Bird-Carreau model as non-Newtonian model with Kepsilon;

https://doc.cfd.direct/openfoam/user-guide-v6/transport-rheology

What I have in my mind is to use steady-state simulation since I cant afford computational cost of LES for 60 patients(completely different geometries and velocities). To do this, I have a plan, just for one case I will do these simulations and compare it with kEpsilon;

1- LES

2-kOmega

3-kkLOmega

https://www.openfoam.com/documentation/guides/latest/doc/guide-turbulence-ras-k-kl-omega.html

4-KOmegaSSTLM

https://www.openfoam.com/documentation/guides/latest/doc/guide-turbulence-ras-k-omega-sst-lm.html

what do you think?

Thanks,

Farzad

Dear Minh Nguyen

I do not think that I am able to use fluid-solid interaction for my modeling due to computational cost.

Thanks,

Farzad

In your problem I would never use steady RANS to predict a rtransition

Dear Filippo Maria Denaro

I am not interested in transition. I just want to use correct model for the flow regime which I do not know if it is turbulent or laminar. In this case, I think using Steady-State is correct.

What do you think about "Gamma-Re Transition Model"? I think I can use it in steady state for my case;

https://en.wikipedia.org/wiki/Gamma-Re_Transition_Model

Thanks,

Farzad

Dear Farzad Farajidizaji

I am not sure. Maybe this document can give you an idea.

https://www2.tulane.edu/~sbc2003/pdfdocs/0811.PDF

Good luck.

Thanks

Again, no. If you would approach such a problem with RANS you are already assuming the flow is turbulent and STATISTICALLY steady. This, if your flow is laminar you will get a wrong solution!!!

You should at least really be running a URANS (Unsteady RANS) simulation. Then time-averaging the results if the flow is indeed statistically steady (the time average will be the same as the ensemble if turbulence is statistically steady by ergodic theorem).