Convergence Problem for Multiphase flow
 

Hello,

I am doing Detailed Simulation of Fuel cell with almost 70 million cells.
The model worked for single phase flow and i got good convergence and results.

But when I change the model to Multi-phase, even the Flow solver is diverging with the same initial conditions as in single phase case and with the results (Pressure and velocity) of single phase as initial conditions for the multi-phase case.

I am playing around with the damping factors, convection methods (1st and 2nd order) but there is no use.

Flow conditions:
steady,Turbulent with k-epsilon, Eulerian multiphase

Output window is showing as some warnings as follows:
Pressure corrections limited on ------
Turbulent viscosity limited on -------
reversed flow

Can someone help me on this.

Thanks and regards,
Naveen

Considering that you have thoroughly checked meshing and physics applied. Like phase interaction properties and multi phase characteristics. If the problem is because of higher pressure gradient then what you can do is reduce the pressure at outlet (near to atmospheric) at first and then start increasing it step by step.

And give more info on the issue like set up properties, BC's, residuals, and whole error message etc for better comment.

Were you able to solve the issue
 

Facing the same kind of issue. I am working on a multiphase mixing tank simulation with turbulence. I have got a converged simulation for a single phase (water) mixed with an impeller. Now I am trying to use the results to initialise a multiphase simulation. In the multiphase setup, additionally air is introduced through a porous sparger (modeled as a surface with an effective diameter of bubbles coming out). Drag and surface tension forces are considered significant. But when the simulation runs the multiphase case it diverges.

Can someone help me out with possible reasons for the same? I can give more details as required.



PS: Mesh is unstructured and mesh quality, orthogonality and aspect ratio is well within limits