A discrete non-local (DNL) outgoing boundary condition for diffraction of surface waves.

A discrete non-local (DNL) boundary condition is used to solve the water waves propagation problem over variable depth. This condition is obtained by means of full solution of the discrete Helmholtz operator in a structured network. We consider a simulation of wave propagation around a circular island located on either a paraboloidal shoal or constant depth bathymetry. Such examples confirm the important improvement in accuracy for the DNL method over standard conditions in the near field. © 1998 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]