Numerical Simulation Of Nearshore Wave Deformation And Calculation Of Longshore Current In Surf Zone

Wave deformation and wave-induced current has been an important topic in coastal dynamics. Longshore current is a phenomenon of phase-average flow movement in the nearshore region occurring after wave breaking, which has great importance on sediment movement, contamination transportation, shoreline evolution and load calculation for the coastal structures. Thus study on the calculation method for longshore current plays an important role not only in practical application but also in theoretical research.In this paper, review on the development of Boussinesq equation, classifying the wave-breaking models based on the Boussinesq equation and research on the longshore currents with numerical model are carried out. Then a numerical wave breaking model based on the fully-nonlinear Boussinesq equations is investigated in terms of its application in calculation of longshore current. The growing process of the longshore current affected by the fully-nonlinear terms is also investigated through numerical tests, which indicates that the fully-nonlinear terms may induce localization of the mean current. It is also found from the numerical tests that the addition of high order vorticity terms in the governing equations can significantly reduce the backward flow circulation outside the surf zone. Modeled results of longshore currents, wave heights and mean water levels are verified by Visser's laboratory data. There is a contrast between Longuet-Higgins's analytic formula of longshore currents and laboratory data.