Numerical simulation of interaction between wave-driven currents and revetment on coral reefs

Abstract

The stability of a revetment breakwater is vital for the safety of islands and reefs formed with reclaimed sand under the action of a complex marine environment. The interactions in wave-reef-revetment systems are complex and difficult to accurately simulate; in addition, it is difficult to describe the dynamic wave pressures distribution by empirical formula, although these parameters are important for the safety of reefs and revetments; hence, more studies are required. In this study, an investigation of the interaction between the wave-driven current on the reef flat and rear revetment breakwater is performed, and the hydrodynamic pressure on the revetment is discussed. A two-dimensional numerical model is established using the Navier–Stokes equation to explore the interaction and calculate the pressure distribution on the revetment, which is verified by an experiment designed and implemented in a wave flume. The simulation illustrates that the wave-driven current is stratified in the vertical direction, and the velocity at the surface is approximately 2–3 times that of the average value, and the maximum flow velocity can reach 13 m/s. By varying the parameters of the geomorphology of the coral reef, the results suggest that for steeper fore-reef slopes, longer reef flats, and larger relative distances, the peak value of the pressure increases consistently. The detailed and sophisticated hydrodynamic pressure distribution on the revetment is obtained, and the numerical results indicate that the fifth-order polynomial can match the regulation of pulsating pressure at the wave surface with the relative submerged water depth.