Wave Interactions With 2D Structures On or Inside Porous Seabed By A Two-domain Boundary Element Method

摘要

Most water-wave theories for use in coastal/offshore design assume rigid, impervious sea bottom. In reality, however, the seabeds are sandy and porous, thus the modification of surface waves by such boundaries has to be taken into consideration in some ocean engineering applications. Reid and Kajiura (1957) and Dean and Dalrymple (1991) developed an analytic solution for linear monochromatic waves propagating over infinitely thick porous seabed using Darcy's law under the assumption of incompressible fluid and flat, non-deformable seabed. In the cases of granular seabed with the assumption of non-deformable bed and incompressible fluid, the interaction of waves with porous boundaries and the resulting seepage flow in the seabed can be adequately described by Darcy's law, which was also experimentally verified by Sleath (1970) and Monkmeyer et al (1983). The Darcy's law is known to be most useful for incompressible fluid, non-deformable porous field and small Reynolds' number. In particular, Sleath (1970) pointed out in his experimental paper that the Reynolds numbers based on grain size and superficial bed-flow velocity are typically small compared to the critical Reynolds number (Chang and Chan, 1998) and consequently Darcy's law will apply in most practical situations.