Analysis of orthogonal wave reflection by a caisson with open front chamber filled with sloping rubble mound

A new combined caisson, including an open window on the front wall and an internal rubble mound with a slope, has been proposed and used in Italy. This study presents a semi-analytical solution to estimate the wave absorbing performance of the new combined caisson with regard to orthogonal wave attack. The internal slope of the rubble mound is assumed to be a series of horizontal steps. Then the matched eigenfunction expansions are used to develop the semi-analytical solution. The square-root singularity of fluid velocity at the upper tip of the front submerged wall is incorporated into the solution to enhance the convergence of calculated results. The new semi-analytical solution is confirmed by an independently developed multi-domain boundary element method solution. Also the predictions of the semi-analytical solution agree reasonably well with experimental data. Based on both the calculations and the experimental data, some useful results are presented for practical engineering. (C) 2014 Elsevier B.V. All rights reserved.