Flow over surface
 

I have a complex surface and want to model the flow over this surface. In particular i want to see how a flow would spill over this surface. I would like to be able to change the amount of flow that would come into an inlet. Does anyone have any suggestions as to how this could be meshed? I think VoF method would be the best way of modelling the free surface but am unsure how to mesh this.

Many Thanks D