Abstract A two-dimensional numerical model was used to study the wave overtopping performance above perforated caisson breakwaters under regular waves. The turbulent flow was simulated by solving the Reynolds Averaged Navier–Stokes (RANS) equations and the k–e turbulence model equations. In the numerical wave flume, the free surface was tracked by the Volume of Fluid (VOF) method, and a relaxation zone was added to avoid the unwanted re-reflection from the inflow boundary. Based on the ideal gas equation at a constant temperature, the pressure change caused by the compressed air inside the wave chamber was incorporated into the numerical model for accurately simulating the wave motion inside the wave chamber. The numerical results of the free surface elevations inside and outside the wave chamber, the wave overtopping discharges and the reflection coefficients of perforated caisson breakwaters were in good agreement with the experimental data. This means that the numerical model is valid in estimating wave action and overtopping on complicated coastal structures with perforated thin walls. The distributions of flow velocity and turbulence kinetic energy (TKE) around the perforated caissons were clarified, which gave a better understanding of the wave overtopping mechanism above the perforated caisson breakwaters. Numerical results showed that the wave energy transferred by the overtopping flows is much smaller than that dissipated by the perforated caisson breakwater. When the relative freeboard (the ratio of the crest freeboard to the incident wave height) of the perforated caisson breakwater was larger than 0.58, the existence of the overtopping flow has no significant influence on the reflection coefficient. Besides, avoiding the air compression inside the wave chamber can effectively reduce the overtopping discharge. Increasing the caisson porosity or the wave chamber width can also reduce the overtopping discharge above the perforated caisson breakwaters.

中文翻译：

---

穿孔沉箱防波堤上方波浪漫顶数值模拟

摘要 采用二维数值模型研究了规则波浪作用下穿孔沉箱防波堤上方的波浪越顶性能。通过求解雷诺平均纳维-斯托克斯 (RANS) 方程和 k-e 湍流模型方程来模拟湍流。在数值波浪水槽中，自由表面通过流体体积 (VOF) 方法跟踪，并添加了松弛区以避免来自流入边界的不必要的再反射。基于恒定温度下的理想气体方程，将波浪室内压缩空气引起的压力变化纳入数值模型，以精确模拟波浪室内的波浪运动。波室内外自由面高程的数值结果，有孔沉箱防波堤的波浪漫溢流量和反射系数与实验数据吻合较好。这意味着该数值模型在估计具有穿孔薄壁的复杂海岸结构上的波浪作用和漫顶时是有效的。阐明了穿孔沉箱周围的流速和湍流动能（TKE）分布，更好地理解了穿孔沉箱防波堤上方的波浪漫顶机制。数值结果表明，溢流传递的波浪能远小于穿孔沉箱防波堤消散的波浪能。当穿孔沉箱防波堤的相对干舷（波峰干舷与入射波高之比）大于0.58时，溢流的存在对反射系数无显着影响。此外，避免波腔内的空气压缩可有效减少溢流。增加沉箱孔隙率或波室宽度也可以减少穿孔沉箱防波堤上方的溢流。