Longitudinal current induced by oblique waves along coastal structures

The time- and depth-averaged equations in a porous medium are used to analy se how dissipation inside an infinitely long vertical breakwater generates an alongbreakwater (AB) current inside the structure. This mean current is transferred seawards and leewards by turbulent diffusion. Based on a theore tical eddy viscosity law, an analytical solution is obtained. The mean curr ent velocity profile depends on characteristics such as water depth, wave h eight, wave period and angle of incidence and on porous medium properties i ncluding porosity and friction. In the neighbourhood of the structure, the simultaneous action of waves and the AB current are taken into account to s tudy the potential sediment transport patterns. Seawards of the structure, the obtained results may help to explain the formation of bars almost paral lel to the breakwater. Under certain circumstances the presence of the brea kwater enhances the sediment transport in the zone closest to the seaward f ace, which may induce scouring at the toe of the structure. (C) 1998 Elsevi er Science B.V. All rights reserved.