[meith]

I find most of VOF methods claim that the velocity field should be exactly divergence free and under this condition VOF could conserve the mass well.

However, I solve the velocity and pressure by SIMPLER algorithme and it cannot obtain the strictly divergence free velocity field. I find the mass is still lost considerably.

Is there any treatment for the problem if the velocity is not divergence free.

In addition, some paper are based on Projection method to solve for velocity. Does this method get the exactly divergence free velocity feild?