Calculation Model for Multiple Breaking Waves and Wave-Induced Currents on Very Gentle Beaches

Abstract

Multiple wave breaking and wave-recovery processes are typical phenomena of wave motions observed on very gentle coastal beaches and have not been accounted for in previous models for the calculation of wave height and longshore current. The present study presents a model that uses a new formulation to calculate wave-energy dissipation in the wave-energy equation and incorporates the formulation into the evaluation of radiation stresses and longshore currents. The key point of the approach is the re-establishment of the reference wave energy Er and the dissipation coefficient Kb in the previous wave-energy dissipation model. The new formula has a small energy dissipation over the wave-recovery region and can properly describe the wave-recovery process in this region. A criterion is established to judge the beginning of wave recovery. The features of radiation stress gradients and longshore currents in the case of multiple wave breaking and wave-recovery processes are discussed. The model is applicable to the cases with or without the presence of the wave-recovery process, and the corresponding validations are made by comparing the calculated results to the laboratory experiment conducted by the present study.