Toward more accurate wave-permeable boundary conditions

Abstract

In order to examine the effects of wave dispersion on the question of whether c* (phase speed) should be fixed or calculated, tests were conducted with a two-level shallow-water model. Once again, the simulations with fixed c* were distinctly superior to those in which c* was calculated at the boundary. A reasonable, though nonoptimal, value for the fixed c* was the phase speed of the fastest wave. In this paper, the approach of Engquist and Majda is used to construct second-order one-way wave equations for situations with nonzero mean flow. The new boundary condition is tested against several alternative schemes and found to give the best results. The new boundary condition is particularly recommended for situations where waves strike the boundary at nonnormal angles of incidence. -from Authors