Reply To: turbulent viscosity ratio and convergence issues

[Rob]

VOF may be less stable as you're tracking a free surface as opposed to a volume fraction. You may also be building up pockets of liquid to then slug: Eulerian may be more suitable to handle the regime change in the flow. 

Stick with PISO, it's better for transient models. I know SIMPLEC has been improved over the years, but still tend not to use it. 

Turbulent viscosity ratio is a warning, but may give you some idea of where the problems are being triggered. Have a look at the local flow field. 

Simple geometry tends to suggest a simple mesh, and far fewer opportunities for poor quality cells, or poor mesh. A complex geometry typically has regions where things need far more care.