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

Accurate velocity boundary conditions are critical to the successful simulation of free surface fluid flow. It is shown in this paper that previous approaches for the assignment of free surface velocity boundary conditions in marker and cell methods artificially introduce asymmetry and can even cause the simulation to break up. New approaches are presented that improve the accuracy of the treatment of free surface velocity boundary conditions. The significant advantages of the use of these new approaches are demonstrated by simulation results obtained for broken dam and cavity filling problems. The new approaches do not artificially introduce asymmetry. Although symmetry is a useful, tangible indicator, it is shown that the significance of the new approaches extends beyond the elimination of asymmetry. Their use enables the successful simulation of problems with realistic values of viscosity and gravity, problems for which breakup of the solution occurs if previous approaches are employed. (C) 1995 Academic Press. Inc.