Abstract An explicit approximation is proposed for velocity distribution and sediment flux above mobile sediment bed beneath current and asymmetric wave. The predicted velocity is decomposed into an oscillatory part and a current part such that the interaction between current and asymmetric wave can be performed directly. The oscillatory part consists of a free stream velocity and a defect function which includes phase lead, mobile sediment bed level and wave boundary layer thickness. The oscillatory part is influenced by the current due to the changes of both mobile sediment bed level and wave boundary layer thickness. The current part is influenced by a wave eddy viscosity in the wave boundary layer and by an apparent wave roughness of the combined wave-current flow outside the wave boundary layer. Eight free variables are required for the approximation, and iterative bottom shear stress and roughness height are applied for the wave boundary layer thickness and mobile sediment bed level. The mobile sediment bed level takes account of the effects of phase lag (phase shift and residual), acceleration and flow asymmetry. Therefore, the mobile bed effect, instantaneous velocity, net velocity and sediment flux in the wave boundary layer can be reasonably presented by the explicit approximation beneath current and asymmetric wave.

中文翻译：

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流动和非对称波下移动沉积床上方的速度和沉积物通量的显式近似

摘要 提出了流动和非对称波作用下移动沉积床上方的速度分布和沉积物通量的显式近似。预测的速度被分解为振荡部分和电流部分，从而可以直接执行电流和非对称波之间的相互作用。振荡部分由自由流速度和缺陷函数组成，缺陷函数包括相位超前、移动沉积物床水平和波边界层厚度。由于移动沉积床水平和波浪边界层厚度的变化，振荡部分受电流的影响。流部分受波边界层内的波浪涡粘性和波边界层外组合波流的表观波粗糙度的影响。逼近需要八个自由变量，并且对波边界层厚度和移动沉积物床水平应用迭代底部剪应力和粗糙度高度。流动沉积床水平考虑了相位滞后（相移和残差）、加速度和流动不对称的影响。因此，波边界层中的移动床效应、瞬时速度、净速度和泥沙通量可以通过在电流和非对称波下的显式近似来合理地呈现。