A NUMERICAL MODEL OF WAVE-RUN-UP AND RESULTING LONGSHORE SEDIMENT TRANSPORT DUE TO OBLIQUELY INCIDENT WAVE

冲刷带动力是计算沿岸输沙速率的一个重要因素。建立了考虑岸线运动边界条件的近岸输沙率分布的数值模型，采用Boussinesq型方程作为控制方程，考虑了非线性和弥散性，并加入了突变模型。在沿岸方向水深均匀的假设下，将岸边坐标和时间合并为一个自变量。近海边界条件包括辐射边界条件，可吸收出流的波浪；岸上边界条件用于模拟波浪斜入射区的运动岸线。将该模型应用于斜入射波的数值计算中，模拟了包括斜浪运动在内的波浪运动，发现该模型能够正确地模拟运动的岸线以及波浪的变形和破碎。该模型采用Dibajnia和Watanabe(1994)提出的泥沙输移公式，得到了断点附近和岸线附近一个峰值和一个峰值的双峰分布，并在此基础上建立了斜入射波作用于近岸直、平行等高线底部地形上的通用数值模型，该模型能较好地模拟波浪变形、激荡运动、近岸水流和近岸输沙速率的分布

Swash zone dynamics is an important factor in computing longshore sediment transport rate. In the present study, a numerical model is developed to predict the onshore distribution of the longshore sediment transport rate by taking into account the moving shoreline boundary condition.Boussinesq-type equations were adopted as the governing equations that include non-linearity and dispersivity, and a breaking model was incorporated. The longshore coordinate and the time were combined into one independent variable under the assumption of a uniform water depth in the longshore direction. The offshore boundary condition included the radiation boundary condition which can absorb the outgoing waves ; the onshore boundary condition was developed to reproduce the moving shoreline in the swash zone.We applied this model to the numerical computations with obliquely incident waves to simulate wave kinetics including swash motion, and found that the model can reproduce the moving shoreline as well as wave deformation and breaking correctly.In addition to the wave field, the nearshore current field was modeled by considering the bottom friction. By incorporating the sediment transport formula proposed by Dibajnia and Watanabe (1994), the model resulted in a bi-modal distribution, with one peak around the breaking point and the other around the shoreline, which has been recognized in the laboratory experiment.As a result, a general numerical model for obliquely incident waves on the bottom topography of straight and parallel offshore contours is developed, which can reproduce non-linear wave deformation, swash motion, longshore current, and onshore distribution of the longshore sediment transport rate