Coastal Wave-Deformation Models Combined with Integrable-Type Infinite Elements

Abstract

An assumption of collinear straight coastlines in the far field, traditionally used in wave models for harbors, is a limitation to wave simulations in the domain extending to infinity, since this assumption is invalid for most real coastlines. By alleviating this limitation based on the geometric-optics approximation, functions of these coastal wave-deformation models are extended to be able to predict wave patterns around the semi-infinite breakwater and convex and concave coasts, such as bulkheads with discontinuous alignment. Mapped infinite elements are also formulated for exterior wave problems. A basic concept in developing is that the true decaying property of scattered waves, i.e. with the modes of r −1/2, r −3/2,…, where r is the radial distance, must be represented directly in infinite elements. To do so, a complementary element is introduced to the infinite element. Infinite element integrals can be expressed explicitly because of analytical integrability due to weak singularity in the infinite mapping. Three test problems for coastal wave-deformation models are solved combined with the cubic infinite element with r −1/2 and r −3/2 decays; this combination technique is found to be effective and accurate for problems of wave scattering.