Exact Nonreflecting Boundary Conditions for the Time Dependent Wave Equation

Abstract

An exact nonreflecting boundary condition is derived for solutions of the time dependent wave equation in three space dimensions. It holds on a spherical artificial boundary and is local in time, but nonlocal in space. It can be reduced to a boundary condition local in space and time for solutions consisting of a finite number of spherical harmonics. The boundary condition is related to the Dirichlet-to-Neumann boundary condition for the Helmholtz equation. It can be used in scattering problems as well as in problems involving nonlinearity in a bounded region of space.