规则波导斯托克斯漂移对污染物输移的影响

Effects of Stokes drift induced by regular waves on pollutant transport

为研究斯托克斯漂移对近岸污染物输移的影响,首先建立波导流和考虑斯托克斯漂移的对流扩散数值模型,通过数模结果与实验结果的比较,研究平直斜坡地形下规则波入射时斯托克斯漂移对污染物输移的影响,波导流模型中波浪场基于波能守恒方程来模拟,波导流场基于Longuet-Higgins提出的辐射应力来模拟,污染物对流扩散模型考虑了斯托克斯漂移的影响。其次,利用一个算例来验证对流扩散模型,结果表明数值模型计算结果与解析解吻合良好。最后,利用该模型模拟了两个实验工况下污染物的输移,数值模拟结果与实验结果吻合良好,表明斯托克斯漂移对近岸污染物向岸线方向的输移有比较明显的影响。

We develop a numerical model that encompasses wave induced current as well as advective and diffusion models to examine the effects of Stokes drift on pollutant transport within the surf zone on a plane beach. We also carried out dye diffusion experiments in the surf zone,and modelled wave-induced currents by applying the concept of radiation stress. We based wave propagation on the equation of wave energy conservation,while the advective diffusion model,including Stokes drift,was used to describe pollutant transport in the surf zone. We then used the alternative direction implicit finite difference method to differentiate between models, and evaluated the validity of these numerical approaches using a Gaussian pulse with a known exact solution. The numerical results of this study are in close agreement with analytical solutions. Finally,we applied our model to simulate pollutant transport within the surf zone on a plane beach. Results show that numerical modeling including Stokes drift more closely agrees with experiments than do results that exclude this drift. Thus,in general,we show that a pollutant will be more obviously transported shoreward in addition to the extent of expected drift. We therefore suggest that Stokes drift plays an important role inpollutant drift within thesurf zone,especially in ashoreward direction.