Flexible Dual Membrane Wave Barrier

Abstract

This paper discusses the performance of a wave barrier consisting of two vertical flexible membranes spaced at a fixed distance apart. The interaction of the membrane system with uniform incident water waves is investigated within the context of two-dimensional linear wave theory. The membranes extend the entire water depth and are tensioned and pinned at both the surface and the seabed. Analytic solutions are developed using eigenfunction expansions for the velocity potential and linear membrane theory. It is found that the transmission and reflection characteristics are highly sensitive to the membrane spacing and tension. These parameters offer the opportunity to tune the barrier system for achieving low energy transmission at a lower membrane tension as compared with a single membrane, and to reflect waves over selected frequency bands. Additional reductions in the transmitted wave energy from viscoelastic dissipation within the membrane are found to be small.