[Cooper24]

I am modelling melting and solidification of solid surrounded by an inert gas. I am using VOF with CSF. It is a 2 phase flow. I am using Explicit VOF with a Courant Number limit of 0.5 for VOF and Global Courant Number as 0.99.
The solution starts good. It converges within few iterations for the first few time-steps. But I see that many a times the Global Courant no. and Explicit VOF Courant No. reach as high as 6 and 1 respectively. Should they not be within the limits given? Also, after few time steps the continuity equation does not show convergence but the velocity and energy equations converge. I have set a limit of 100 iterations/time-step and continuity equation is only creating problem.
Any help is much appreciated on how to solve the issue with continuity equation convergence and why the courant numbers are showing the above said behavior.
Thanks in advance.