Numerical simulation of three-dimensional lee waves behind an isolated hill

Stably stratified fluid flow over smooth hills is an important process in environmental fluid mechanics. The aim of this article is to point out some of the key features of this phenomenon from both the physical and the mathematical modeling point of view. Three-dimensional laminar flow over a smooth, axisymmetric hill is considered for a range of values of the Froude number and the Reynolds number. The numerical simulations are performed on the basis of the Boussinesq approximation model, solved with a high-resolution compact finite-difference numerical scheme. The numerical results obtained are discussed with respect to the observed physical phenomena, taking into account the separate role of varying the velocity (Reynolds number) and stratification (Froude number). The mathematical modeling and numerical solvability issues encountered are discussed in detail, pointing out the key role of the computational setup and boundary conditions. (C) 2019 Elsevier Inc. All rights reserved.