The aim of this work was to investigate the reshaping mechanisms of a reshaping berm breakwater (BB) by assessing the results of a two-dimensional numerical model in OpenFoam. The flow inside and outside the breakwater was numerically simulated. The initial and reshaped form of the breakwater was modelled using the Darcy–Forchheimer equation and k–ϵ closure model. The numerical model was calibrated with and validated against experimental data of wave-induced pressure and water-level fluctuations inside and outside the breakwater. Both the initial and reshaped BB were evaluated for calibration and validation processes. The results show that the minimum run-down level on the breakwater slope is a critical area for armour instability due to outward driving forces caused by the critically synchronised outward flow and excess pressure gradient. Moreover, parallel downward flow occurs during a wave run-down, which can push the displaced armour down the slope. After reshaping, the breakwater profile has a milder slope than the initial profile, and the outward forces due to the excess pressure gradient are reduced to less than one-half of their initial amount, a result of the change in breaker type. Accordingly, the reshaped profile is modified to harmonise with the new flow field conditions.

中文翻译：

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重塑防波堤波浪诱导流的机制

这项工作的目的是通过评估 OpenFoam 中二维数值模型的结果来研究重塑护堤防波堤 (BB) 的重塑机制。对防波堤内外的流动进行了数值模拟。使用 Darcy–Forchheimer 方程和k – ε对防波堤的初始和重塑形式进行建模闭包模型。数值模型根据波浪引起的压力和防波堤内外水位波动的实验数据进行了校准和验证。对初始和重塑 BB 进行了校准和验证过程评估。结果表明，由于临界同步向外流动和超压梯度引起的向外驱动力，防波堤斜坡上的最小破败水平是装甲失稳的关键区域。此外，在波浪下降期间会发生平行向下的流动，这可以将移位的装甲推下斜坡。重塑后，防波堤剖面的坡度比初始剖面更平缓，由于破碎锤类型的变化，由超压梯度引起的向外力减少到初始量的二分之一以下。