Numerical Model for Wave Refraction-Diffraction near Pearl River Estuary, China

Abstract

Using the elliptic mild-slope equation to resolve wave fields in large coastal areas requires enormous computer resources, thus imposing a great restriction on the applicability of this equation for practical engineering problems. An improved numerical model based on the mild slope RCPWAVE model has been developed for computing wave refraction and diffraction in a large coastal area with complex coastline near the Pearl River estuary, in China. An operator splitting method is employed to solve the wave action equation, in which the advection terms are resolved by the Eulerian-Lagrangian method to increase numerical stability and the other terms are discretized by the implicit finite-element method to fit complex coastline geometries. A stable and efficient nominal-time finite-node method is proposed to solve the nonlinear irrotational wave number equation for wave directions. Numerical tests on wave propagation proved that the present model has significant improvements in model stability and efficiency over the RCPWAVE model. Different swell transformation scenarios in the Pearl River estuary have been simulated by the model. For such a large and complex estuarine region, the model simulated the wave distributions reasonably well, with good efficiency, and it also produced results that closely matched the field measurements collected at two wave gauges.