The swash zone is an important region for the coastal morphodynamics. Often, model studies of the swash zone use depth-averaged models. These models typically assume a vertically uniform velocity and sand concentration for calculating the sand transport flux. However, this assumption is not always accurate in the swash zone. In order to investigate the vertical distribution of velocity and sand, we use a depth-resolving model that is able to capture these vertical variations. We simulate the flow and suspended sediment transport induced by bichromatic waves using a 2DV depth-resolving RANS model. Our verification of the model shows that special care needs to be taken to deal with bubbles in 2DV simulations. Furthermore, we show that turning off the (Wilcox, 2006, 2008) limiter for turbulence, increases the modelled turbulent kinetic energy that is induced by wave-breaking, resulting in improved predictions of sediment concentrations. Using the depth-resolving model, we show that the vertical distribution of velocity and sand is far from uniform in the swash zone. The results show that if one assumes vertically uniform depth-averaged velocities and concentrations, one can overpredict the sediment flux by 50%.

中文翻译：

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自由表面模拟和破浪湍流对冲刷带泥沙输运深度分辨模拟的影响

冲刷带是海岸形态动力学的重要区域。通常，斜流带的模型研究使用深度平均模型。这些模型通常假设垂直方向均匀的速度和沙子浓度来计算沙子传输通量。然而，这种假设在斜流区并不总是准确的。为了研究速度和沙子的垂直分布，我们使用能够捕获这些垂直变化的深度分辨模型。我们使用 2DV 深度分辨 RANS 模型模拟双色波引起的流动和悬浮沉积物输送。我们对模型的验证表明，在 2DV 模拟中处理气泡时需要特别小心。此外，我们表明关闭（Wilcox，2006，2008）湍流限制器会增加由波浪破碎引起的模拟湍流动能，从而改善沉积物浓度的预测。使用深度分辨模型，我们表明冲刷区速度和沙子的垂直分布很不均匀。结果表明，如果假设垂直方向均匀的深度平均速度和浓度，则可以将沉积物通量高估 50%。