Numerical Study of Interaction between Flow Field and Free Surface in a Two Dimensional Cavity

It is very important to implement correct boundary condition at the free surface of a flow field. A 2D cavity with movable bottom has been solved with a numerical method which can use two types of boundary conditions at the free surface. The numerical results show that in these types of flows، which non-hydrostatic pressure gradients have not dominant direction، and they are small in the whole of the flow field، even a little displacements of the free surface have very large effects on the flow field configuration. Therefore، ignoring the free surface displacements in the numerical solution leads to some errors in flow behavior predictions.