Author(s)

S. Alliney

Abstract

A revisitation of the infinite element method for water wave diffraction problems S. Alliney Istituto di Matematica Generate e Finanziaria, Universitd di Bologna, 40126 Bologna, Italy ABSTRACT Exterior wave problems are often solved using infinite elements as an alternative to B.E.; good results have been obtained with shape functions which combine a r"^ decay with exponential dumping. In this note, we will show that such asymptotic beha- viour can be justified by taking into account the fluid-surface in- teraction at the sea bottom. INTRODUCTION In the classical potential theory for water waves (see e.g. [1]), we consider an irrotational flow, and the related velocity poten- tial *I>(x,y,z;t), such that v=grad W. Moreover, if we seek a solu- tion, that is simple harmonic in time, the potential function can be decomposed as *P(x,y,z;t) =O(x,y,z) exp(-icot), co being the angular frequency. A further simplification can be obtained with two-dimensional models, that we can deduc

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