This paper presents three dimensional (3D) numerical modeling of local scour around a single pile under the combined action of waves and currents. A semi-coupled hydrodynamic and morphological model (REEF3D) is used in this study which solves the Reynolds-averaged Navier–Stokes (RANS) equation with k-$\omega$ turbulence model closure. The Exner equation is used to calculate the changes in bed elevation. The use of the Level-Set method is done to capture the changes in the free surface. Realistic scour and deposition calculations are aided with the use of modified critical bed shear stress reduction formulation on a sloping bed supplemented with the use of Sand Slide algorithm in the morphological model. The scouring process is modeled in this study using a reduced-length numerical wave tank with wave generation and wave absorption implemented using active wave absorption method. The model is validated for the numerical modeling of local scour around a single pile in steady current, waves alone, and combined wave–current environment. The validated model is used to analyze the effect of Keulegan–Carpenter ($KC$) number and combined wave–current parameter $\left(U_{cw}\right)$ on normalized equilibrium scour depth. It is found that the normalized equilibrium scour depth for scour under waves alone, waves combined with weak currents, and waves combined with mild current do not significantly differ for flow developed in a low $KC$ number environment. However for waves combined with strong currents the normalized equilibrium scour depth increases significantly. For large $KC$ numbers, the normalized equilibrium scour depth is found to have increased with an increase in $KC$ number as well as combined wave–current parameter $\left(U_{cw}\right)$.

本文介绍了在波浪和水流的共同作用下，单个桩周围局部冲刷的三维 (3D) 数值模拟。本研究中使用了半耦合流体动力学和形态学模型 (REEF3D)，它使用 k-求解雷诺平均 Navier-Stokes (RANS) 方程。$\omega$湍流模型闭合。Exner 方程用于计算床高程的变化。使用 Level-Set 方法来捕捉自由表面的变化。在斜床上使用修正的临界床剪切应力减少公式，并辅以形态模型中的 Sand Slide 算法，可帮助进行现实的冲刷和沉积计算。在这项研究中，冲刷过程是使用一个减少长度的数值波浪水槽建模的，波浪产生和波浪吸收是使用主动波浪吸收方法实现的。该模型适用于在稳定流、单独波浪和波浪-流组合环境中单个桩周围局部冲刷的数值模拟。验证模型用于分析 Keulegan-Carpenter ($钾C$) 数和组合波流参数 $\left({你}_{C瓦}\right)$归一化平衡冲刷深度。发现单独在波浪下冲刷、波浪与弱水流结合以及波浪与温和水流结合的归一化平衡冲刷深度对于在低处发展的流动没有显着差异。$钾C$数环境。然而，对于与强电流相结合的波浪，归一化平衡冲刷深度显着增加。对于大$钾C$ 数字，发现归一化平衡冲刷深度随着 $钾C$ 数以及组合波流参数 $\left({你}_{C瓦}\right)$.