High order absorbing boundary conditions without high order derivatives

The application of high order absorbing boundary conditions in numerical simulations of wave propagation will generally result in good absorption of outgoing waves. However, high-order absorbing boundary conditions usually have complicated expressions and involve high order derivatives which can be quite troublesome in their implementation. A technique called the multi-absorbing boundary condition is presented. This technique involves the implementation of absorbing boundary conditions in such a way that high order derivatives are not involved. The application of the proposed method to Higdon´s (1987) and Lindman´s (1975) boundary conditions is considered by way of illustration.<>