The effect of porosity of submerged break water structured on non-breaking wave transformation

Abstract

Development of an innovative porous submerged breakwater structure which could be used for the purpose of coastal restoration is underway in the Coastal & Offshore Engineering Institute’s research laboratory. Prior to developing the structure, laboratory investigations on models (typifying porous submerged breakwater structures) that could provide experimental information of the influence of porosity on non-breaking wave transformations have been undertaken. A series of tests to study the effect of porosity of submerged breakwater model structures on the process of non-breaking wave transformations have been carried out. A hollow framework-shaped test model was used. Three models each with three different porosities ranging from 0.40 to 0.80 were constructed. From laboratory tests, results obtained have been analysed to check the performance of the models to attenuate waves. Test results have indicated that the transmission coefficient, KT increased with increasing model porosity. The wave reflection coefficient, KR of the model tested ranged from 0.01 to 0.31. Energy loss of the primary waves was found to be highest when the parameter kd was equal to 1.9 and lowest when the porosity of the model was found to be large.