||July 21, 2009 11:21
Convergence problem with thermal phase change model under low velocity conditions
I have a tutorial from Ansys about how to use thermal phase change model (Multiphase Workshop 7). So I set my problem very similar to what are in the example: inhomogeneous multiphase flow (water and water vapor), k-epsilon with medium intensity. When I have a velocity inlet of 0.5 m/s, convergence is beautiful and mass imbalances are excellent. However, when I lower the inlet velocity to 0.05 m/s, problem arises and this is the only parameter I change. It doesn't converge at all, and mass imbalances go crazy. I checked the Re number for velocity of 0.05 m/s, it is almost 10000, which shows that it is a turbulent flow. I try k-omega model, but it doesn't help. Any suggestions?