Reply To: Multiphase VOF simulation of a rotating capillary tube

[Rob]

Reverse flow is common, I agree, but check which phase is reversing.   Try rotating the fluid zone & wall at zero relative. Should give much the same effect but may resolve some of the issues. The other comment from a colleague was to drop the time step alot further: there can be a situation where too high a step is stable because everything is smoothed out.