以數值模擬分析孤立波之溯升與破碎

Abstract

本研究透過 OpenFOAM 模擬孤立波之溯升，使用 RANS 方程式以及浮力修正紊流模型 (buoyancy-modified k − ω SST turnulence model)，使用相同的入射波條件，傳遞上斜率為 1/2 至 1/100 的斜板，分析斜板斜率對孤立波的影響，分析不同破碎型態的特徵及性質。模擬結果顯示，總能量在溯升期間的消耗隨著斜板越緩消耗百分比越高。同時，崩捲型破碎 (plunging) 顯示出瞬間最劇烈的紊流動能，而溢出型破碎 (spilling) 的破碎總時長最長，無破碎 (no breaking) 及洶湧型破碎 (surging) 的能量消耗則非常低。能量變化圖上，透過動能與位能之間的變化，也可以看到斜板的反射與波浪淺化的現象。此外，前人使用的破碎型態分類標準在本模擬中也適用，僅溢出型 (spilling) 在更陡的斜板上就能夠觀察到。

The study simulates the run-up of solitary waves using OpenFOAM, applying the RANS equations and the buoyancy-modified k − ω SST turnulence model.Under identical incident wave conditions, slopes ranging from 1/2 to 1/100 were tested on inclined plates to analyze the impact of slope on solitary waves and to examine the characteristics and properties of different breaking types. The simulation results indicate that the percentage of total energy dissipation during the run-up increases as the slope becomes gentler. Additionally, plunging-type breaking shows the most intense instantaneous turbulent kinetic energy, while spilling-type breaking has the longest total breaking duration. Energy dissipation in non-breaking and surging-type breaking waves is minimal. The energy variation figure reveals the reflection and wave shoaling phenomena on the slope through the changes in kinetic and potential energy. Moreover, the classification standards for breaking types used in previous studies is also applicable in this simulation, except that spilling type can be observed even on steeper slopes.