[roshanak878]

Hi
I am working in a model consist of rotation and multi-phase flow. I am using openFOAM and my solver is reactingTwoPhaseEulerFoam which is Two-Fluid solver. I have inlet and outlet and there is an inner cylinder that is rotating. I used MRF for rotation. I run my model and after a long time, I did not see a steady-state condition. Because I used MRF, supposedly result only after reaching steady state is reasonable. since in this solver Dynamic mesh is not added, I stuck to MRF. Can you help me with it? any idea how I can tackle this problem? I saw discussions in the CFD forum that talk about transient MRF. I compared two similar cases (mixerVessel2D) by running in reactingTwoEulerFoam+MRF and VOF+Dynamic mesh. Apparently the results are the same with some error. Can we use MRF for the transient regime? I appreciate it if you help me with it

Regards
Roshanak

[geth03]

multiphase fluid movement is highly transient bc of phase interaction in every timestep.

mrf is a steady-state approximation.

you will mix two different time approaches.

[vivjk94]

Originally Posted by roshanak878

Hi
I am working in a model consist of rotation and multi-phase flow. I am using openFOAM and my solver is reactingTwoPhaseEulerFoam which is Two-Fluid solver. I have inlet and outlet and there is an inner cylinder that is rotating. I used MRF for rotation. I run my model and after a long time, I did not see a steady-state condition. Because I used MRF, supposedly result only after reaching steady state is reasonable. since in this solver Dynamic mesh is not added, I stuck to MRF. Can you help me with it? any idea how I can tackle this problem? I saw discussions in the CFD forum that talk about transient MRF. I compared two similar cases (mixerVessel2D) by running in reactingTwoEulerFoam+MRF and VOF+Dynamic mesh. Apparently the results are the same with some error. Can we use MRF for the transient regime? I appreciate it if you help me with it

Regards
Roshanak

MRF is steady state approach means that your inner cylinder wont physically rotate but there will be velocity applied to the velocity near the inner cylinder. same applies for VOF, avoid both. Transient is your only hope. Try using fluent. you can use mesh motion in transient. If you have a good system or workstation, you can use dynamic mesh.
if you have a weak system and want to work with dynamic mesh then coarsen the mesh