NOTE ON OPEN BOUNDARY-CONDITIONS FOR ELLIPTIC FLOWS

Four different open (outflow) boundary conditions are compared and evaluated by using the incompressible PoiseuillelBenard flow in a two-dimensional rectangular duel as a test case. The conditions are: Simple upwinding, linearly and quadratically weighted upwinding, and vanishing of a linearized convective derivative. The upwinding conditions generate significant reflection of outgoing waves back into the computational domain, while the convective condition presents little reflection. This last condition, which is a Sommerfeld-type radiation condition, is recommended for use at boundaries where a net outflow of fluid occurs. © 1990 by Hemisphere Publishing Corporation.