A COMPARISON OF OUTFLOW BOUNDARY CONDITIONS FOR THE MULTIDOMAIN STAGGERED-GRID SPECTRAL METHOD

Abstract

Abstract This article investigates four outflow boundary conditions (BCs) for use with the multidomain spectral method (D. A. Kopriva, J. Comput. Phys. , vol. 244, pp. 142-158, 1998). The objective is to find low-reflective, stable BCs suitable for use in direct numerical simulation (DNS) of turbulent flows in complex geometries. This investigation is focused on outflow BCs, which are critical in DNS. The methods were tested on a two-dimensional Poissueille flow, a vortex propagating through an outflow boundary, and a transitional flow over a rectangular cylinder. The best results were found by specifying the exit pressure and using a linear Riemann solver to compute the velocity and density. Temporal damping in the subdomains bordering the outflow boundary improved the results in specific cases.