VELOCITY BOUNDARY-CONDITIONS FOR THE SIMULATION OF FREE-SURFACE FLUID-FLOW

Accurate velocity boundary conditions are critical to the successful s imulation of free surface fluid flow. It is shown in this paper that p revious approaches for the assignment of free surface velocity boundar y conditions in marker and cell methods artificially introduce asymmet ry and can even cause the simulation to break up. New approaches are p resented that improve the accuracy of the treatment of free surface ve locity boundary conditions. The significant advantages of the use of t hese new approaches are demonstrated by simulation results obtained fo r broken dam and cavity filling problems. The new approaches do not ar tificially introduce asymmetry. Although symmetry is a useful, tangibl e indicator, it is shown that the significance of the new approaches e xtends beyond the elimination of asymmetry. Their use enables the succ essful simulation of problems with realistic values of viscosity and g ravity, problems for which breakup of the solution occurs if previous approaches are employed. (C) 1995 Academic Press. Inc.