ABSTRACT

Based on the linear potential theory, a quadratic pressure drop boundary condition is imposed on the perforated plate to develop a new analytical solution for wave reflection by a horizontal perforated plate wave absorber. The new analytical solution is developed by combing a velocity potential decomposition method and an iterative calculation algorithm. The analytical results are in excellent agreement with the numerical results of an iterative multi-domain boundary element method solution, and agree reasonably with experimental data in literature. The reflection coefficient of the wave absorber is examined by calculation examples, and some useful suggestions on practical application are recommended.

INTRODUCTION

A submerged horizontal perforated plate attached to the vertical end wall of a wave flume can serve as a wave absorber, which was initially proposed by Wu et al. (1998). It is found that the horizontal perforated plate can suppress both the wave run-up on the vertical wall and the reflected wave height. When the parameters of the horizontal perforated plate are well determined, it can achieve effective wave absorbing performance. Some scholars (Cho and Hong, 2004; Cho and Kim, 2008a; Cho and Kim, 2008b; Ko and Cho, 2018) used the analytical, numerical and experimental methods to investigate the wave absorbing performance of the wave absorber with horizontal and inclined perforated plates, and gave useful suggestions on how to enhance the wave absorbing performance of the horizontal/inclined perforated plates.

In this s t u d y, a new analytical solution for wave reflection by a horizontal perforated plate wave absorber is developed. Different from the previous analytical solutions for wave interaction with the horizontal perforated plate wave absorber, a quadratic pressure drop boundary condition (Molin, 1992; Molin and Remy, 2015; Liu and Li, 2017) is imposed on the perforated plate in the present study. Such a quadratic pressure drop condition can directly consider the effect of wave height on the wave energy dissipation by the perforated plate. Due to the use of nonlinear (quadratic) pressure drop condition, the standard matched eigenfunction expansion method cannot work. Alternatively, an effective approach to solve this kind of boundary-value problem may be the velocity potential decomposition method, which was proposed by Lee (1995) for solving the heavy radiation problem of a floating box. The velocity potential decomposition method with an efficient iterative calculation algorithm (An and Faltinsen, 2012; Molin and Remy, 2013; Liu and Li, 2017) is used to develop the present analytical solution.

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