Outflow boundary conditions for low-Mach buoyant computational fluid dynamics

Abstract

General issues with outflow boundary conditions are discussed, as are the issues specific to flow with buoyancy such as unphysical build-up of fluid at the outflow boundary. Different solutions to these problems are detailed. The sponge-layer approach is used to model the outflow boundary in buoyant jets. The successes and shortcomings of the sponge-layer approach are made clear through comparisons with long domain simulations.