基于两相湍流珊瑚礁地形的波浪数学模型

Numerical Modeling of Two-Phase Turbulence Closure for Wave Transformation over a Coral Reef

珊瑚礁地形的波浪非常复杂,礁坪破碎后的波浪对礁体、防波堤等影响很大。为了更好地了解珊瑚礁地形下规则波的传播变形特征,文中基于雷诺平均的纳维埃-斯托克斯方程建立了珊瑚礁地形上的波浪数学模型,其中湍流模型采用两相的k-ωSST方程,数值模拟在OpenFOAM开源工具中进行。本模型通过文献中的物理实验数据进行验证,分析了珊瑚礁地形上的波高、增水和波面形态变化,并与标准k-ωSST模型的结果进行比较,结果表明:文中模型能有效减轻自由表面附近过度产生的湍流动能,波高和增水的模拟结果相比标准k-ωSST模型的更加准确;波浪在珊瑚礁地形上破碎时破波区的湍流动能主要集中在波峰附近,波谷的湍流动能则很小;在湍流动能的影响下,模型在破碎点处的波高减小、减水增大,破碎后的波能耗散增大。文中波浪数学模型可应用于珊瑚礁工程设计的波浪计算中。

Wave transmission over a coral reef is very complex,and the wave breaking over the reef flat has significant impacts on the reefs and the breakwaters.In order to better understand the characteristics of regular waves propagating over the coral reefs,a wave numerical model based on Reynolds-Averaged Navier-Stokes equations was constructed.The turbulence model was designed with two-phase k-ωSST equations.The numerical simulation was carried out in open source library,OpenFOAM.The numerical model was validated with the experiments in the lite-rature.Wave heights,wave setups and surface elevations on the coral reef were analyzed and compared with the results of standard k-ωSST model.The results show that two-phase model can significantly weaken overproduction of turbulence energy near the free surface and provide better predictions of wave height and setup than standard model.Wave breaking in the surf zone causes large turbulence energy at the wave crest while little at the wave trough.Under the effects of turbulence energy,the wave height decreases and the wave setdown increases at the breaking point,and the energy dissipation increases after the wave breaking.This numerical model can be used for calculating wave breaking in the design of harbor construction.