Experimental study on the performance characteristics of porous perpendicular pipe breakwaters

Abstract

Several investigations of the physical properties of wave–structure interactions and absorption of structures in coastal areas discussed the development of several permeable and porous breakwaters. This article addresses highly-pervious dense pipe with small apertures, which can be beneficial for convection and interchange of sea water within the harbor district, and furthermore, perform effectively in wave absorption. This study investigates the dissipation of porous perpendicular pipe breakwaters, and presents laboratory investigations of wave transmission from permeable pipe breakwaters with different wave conditions and various combinations of diameter and tube length. Since wave energy is mainly dissipated due to drag and interception of the resultant motion by the pipe breakwaters, the reflectivity of such effects is discussed by the evaluation of partly reflected and transmitted ratio. Consequently, the performance of the pipe breakwater for predicting the wave transmission coefficient is investigated. Experimental results reveal that dissipation and/or reflection is more effective when decreasing pipe diameter than increasing pipe length, specifically when dimensionless frequency σ2h/g>1.5. Nevertheless, the effect is relatively inconspicuous when σ2h/g<0.75. A partial outcome demonstrates the influence of pipe diameter and variations of reflection coefficients corresponding with dimensionless frequencies for incident waves with various wave heights.