Numerically Nonreflecting Boundary Conditions for Multidimensional Aeroacoustic Computations

Many compressible ow and aeroacoustic computations rely on accurate nonre ecting or radiation boundary conditions. When the equations and boundary conditions are discretized using a nitedi erence scheme, the dispersive nature of the discretized equations can lead to spurious numerical reections not seen in the continuous boundary value problem. These re ections can lead to poor convergence to a stationary state, and can lead to selfforcing of ows. We have constructed numerically nonre ecting boundary conditions which account for the particular nite-di erence scheme used, and are designed to minimize these spurious numerical reections. These extend our earlier work on onedimensional boundary conditions to the multidimensional case. Stable boundary conditions which are nonre ecting to arbitrarily high-order-of-accuracy are obtained. Various test cases are presented which show excellent results.