Numerical Simulating of the Interaction of Vertical Fixed Multiple Membranes with Gravity Wave

Abstract

Abstract. In deep sea or temporary application, the floating breakwater should be best used to attenuate the surface wave. But the most difficulty of floating breakwater is to decrease long wave length wave. Bragg resonance condition appears while incident surface water wavelengths are approximately twice the periodic structure wavelengths, and large amounts of incident wave energy are reflected. In recent years, flexible membrane structure, with its numerous advantages, has attracted the attention of the coastal and ocean engineers and researchers. Although Bragg resonance is investigated by using diffirent analytical methods, it is not found by using CFD method. Therefore, in this paper, we use commercial software code FLUENT to numerical simulating the interaction of surface grivaty wave with multiple veitically fixed membranes with constant gaps. At the beginning, we verified the numerical technology by simulating the wave making and the interaction of wave with single membrane; then, we computed 4 diffirent length veitically fixed multiple membranes. The results show that the transmission coefficient is small and decline obviously with the membrane lengthened when incident surface water wavelengths are approximately twice the membrane gap. However, we need to simulate more wave lengthes to find whether there is the strong reflection induced by Bragg resonance. The works in this paper are the base about more studies on Bragg resonance being applied to floating breakwater.