随机波波生流的数值模拟

Numerical Modelling of Nearshore Currents Induced by Irregular Waves

为了更合理地反映实际海浪的随机性 ,作者采用随机波折射 -绕射模型和波生流模型对近岸海域中的波生流进行数值模拟 ,探讨不同条件下随机波波生流的流场结构。通过计算发现除地形对随机波波生流有明显影响外 ,波生流的大小同入射波高及波浪破碎关系密切 ,其流向特别是离岸流的位置与入射波向有关。

Nearshore currents due to the action of breaking w aves are a main dynamic factor of sediment transport and pollutant dispersion in the coastal areas. So over the last two decades, a great many numerical models have been developed to compute the nearshore currents. However, most of these mo dels are based on the regular wave theory. In order to describe the nearshore cu rrents more accurately, it is necessary to take into account the effects of wave irregularity. The aim of the study is to present a numerical model of the nearshore currents i nduced by irregular waves. In this model, by means of a time-dependent mild slop e equation, the random wave fields in terms of directional spectra are firstly d etermined to simulate the deformation of irregular waves due to wave refraction, diffraction and breaking. Then, the radiation stress fields are obtained by the numerical integration of the directional spectra with respect to wave direction s and frequency. finally, the velocity fields of nearshore currents are calculat ed by use of depth and one wave period averaged two-dimensional equations. it is seen from the calculation that the magnitude of nearshore currents is closely r elated to the incident wave height and direction in addition to the bottom topog raphy.