An Experimental Study of Wave Absorbers

Abstract

Large-scale experimental studies were conducted on two types of wave absorbers, as an extension of earlier small-scale work. The first absorber, and the one of primary interest, was a discontinuous permeable absorber with a surface slope of 12 degrees. Two types of permeable materials-- ( a) crushed rock and (b) rectangular bars--were investigated. Several modifications of the basic design were studied, including various thicknesses of permeable layer. On the basis of the experimental studies, an optimum thickness of permeable layer was selected. The use of the rectangular-bar construction was recommended. Brief tests were run on the second type, a short absorber, which was being considered for use around the periphery of a rotating-am basin. The tests indicated that a surface slope of 15 degrees and a thin layer of permeable material produced the best results. The absorber was restricted to a very short length and produced high reflection coefficients, but it materially reduced the settling time of the basin.