surface monitors in VOF
 

I am modeling free surface flow in an open channel using FLUENT software. I have defined a surface monitor for the massflow on top boundary which is subjected to atmospheric pressure. After few thousand iterations, results (residual monitor) shows mass inbalance between inflow and outflow. The surface monitor (on top) shows 4% of the fluid is escaping from the top boundary. What does it mean? please explain me whether it is normal that fluid escapes from free surface boundary. How to correct it if it is not correct.

Thanks in advance

Well, that could related to computational issues. Your mesh might not be sufficiently fine to compute and give you a converged solution. I would try making a finer mesh, as well as using a smaller time step. Also, you can try using some other discretization method and compare your results.

Hi Jha,

Thank you so much.

Prashanth