Multiphase and Non Newtonian fluid
 

Hi all,

Anyone have any experiences handle multiphase flow case with the involvement of Non newtonian fluid in one of the phases?
My case is the simulation of the blood vessel.

Below is the phases that I am going to model
1) plasma : Newtonian Fluid (phase 1 with the 55 % volume fraction)
2) RBC : Non newtonian Fluid (Phase 2 with the 44 % volume fraction)
3) Leukocytes : Newtonian (Phase 3 with the 1% volume fraction)

I have set on the multiphase flow (Eulerian), using SST k-omega model (turbulent flow). I defined the RBC non newtonian model to CArreau Model.

I run the simulation for steady case as initial condition. After 380 iterations no error detected.

Then I run the simulation for unsteady case. I set the inlet boundary condition to be mass flow rate profile (1 s = 1 cycle).

For unsteady, I need to run until 5th cycle.
After 2 cardiac cycles, the error : pressure correction detected.

Why it is like this?


Besides,in order to detect the cause of error, I have run the simulation using the same mesh element for turbulent, single phase case (Newtonian)
The simulation can successfully run (both for steady and unsteady/transient).

So, I guess one of the reason for the model to fail is because of multiphase flow set up. Is my assumption correct? Or is it because of the involvement of Non newtonian fluid in one of the phases?
Is there any suggestion for multiphase flow? How to solve the problem.

Thank you

Regards,
Naimah