Simulation of non-hydrostatic, density-stratified flow in irregular domains

A numerical model has been developed for simulating density-stratified flow in domains with irregular but simple topography. The model was designed fo r simulating strong interactions between internal gravity waves and topogra phy, e.g, exchange flows in contracting channels, tidally or convectively d riven flow over two-dimensional sills or waves propagating onto a shoaling bed. The model is based on the non-hydrostatic, Boussinesq equations of mot ion for a continuously stratified fluid in a rotating frame, subject to use r-confrgurable boundary conditions. An orthogonal boundary fitting co-ordin ate system is used for the numerical computations, which rely on a fourth-o rder compact differentiation scheme, a third-order explicit time stepping a nd a multi-grid based pressure projection algorithm. The numerical techniqu es are described and a suite of validation studies are presented. The valid ation studies include a pointwise comparison of numerical simulations with both analytical solutions and laboratory measurements of non-linear solitar y wave propagation. Simulation results for flows lacking analytical or labo ratory data are analysed a posteriori to demonstrate satisfaction of the po tential energy balance. Computational results are compared with two-layer h ydraulic predictions in the case of exchange flow through a contracting cha nnel. Finally, a simulation of circulation driven by spatially non-uniform surface buoyancy flux in an irregular basin is discussed. Copyright (C) 200 0 John Wiley & Sons, Ltd.