I am trying to model a perforation in the side of a pipeline. The pipeline has gas flowing through the main body, with water in the perforation. I am interested in the interface between the water and gas, and so I am using the VOF multiphase model, as the flow is stratified. Because I am implementing the VOF model, I am using the pressure-based pseudo transient solver. I am also using the standard k-omega turbulence model because I am interested in eddy formation.
I am experiencing convergence issues with this simulation. Namely, whenever I run it using either the iterate or dual-time-iterate command, I get the following errors:
"Experiencing convergence difficulties-temporarily relaxing adn trying again...
Divergence detected in AMG solver: pressure coupled / k / omega / phase-1-species-0...etc.
These errors are given immediately, prior to any iterations completing.
I have adjusted my URFs and flow courant number. I am using the following values, and still experiencing these errors:
Flow courant number: 10
Body forces: 0.75
Turbulence kinetic energy: 0.5
Turbulent viscosity: 0.75
Phase species: 0.75.
I am using the variable time stepping method.
Is there any other things I should try to do to improve convergence? Or, as I am getting these errors, is it probably something wrong with my mesh or setup? Another thing that I am worried about is that my model does have cell zones that contain solid sections, could that be incompatible with the VOF model?
Thanks so much for the help!