WAVE DIFFRACTIONS BY ROWS OF VERTICAL CYLINDERS OF ARBITRARY CROSS SECTION

Abstract

Wave diffractions by a number of (a group of or a row of) vertical cylinders have been investigated in connection with, e.g., multilegged offshore structures (Spring and Monkmeyer(1974), Ohkusu(1974), Chakrabarti(1978), Mciver and Evans(1984), etc.); Wave-Power absorption devices (Miles (1983), Falnes(1984) , Kyllingstad(1984) , etc.); Wave barrier systems (Massel(1976), Kakuno and Oda(1986), etc.). Most of the previous works were, however, mainly aimed at the wave diffractions by cylinders of circular cross section and/or by cylinders of relatively small dimensions compared to wave length. In this paper, we describe a simple yet versatile analytical method to solve wave diffractions by infinite rows of vertical cylinders. In the method, it is assumed, in addition to usual linearised small amplitude assumptions, that: the row of cylinders is composed of infinite number of surface-piercing evenly spaced equal cylinders fixed on sea bottom; incident wave direction is perpendicular to the row; the number of rows may be arbitrary, at least in principle; the cross sectional shape of the cylinders may be arbitrary as long as it is symmetrical with respect to the incident wave ray; and the cylinders are relatively large compared to incident wave length so that inertial forces are predominant to drag forces.