非淹没刚性植物对海啸作用下海堤水动力特性影响数值模拟研究

基于非静压单相流模型NHWAVE建立了高精度数值波浪水槽。通过设计不同的计算工况,系统研究了非淹没刚性植物对海啸作用下海堤周围水动力特性的影响。着重分析了不同入射波高、不同植物分布密度以及不同植物分布宽度条件下海啸波沿程波形特征以及海堤堤顶越浪流空间分布特征。结果表明:不同入射波高、植物分布密度以及植物宽度条件下,堤顶流厚度和水体流速具有明显单调的变化趋势,并且随着植物分布密度和宽度增大,波能衰减增大;随着入射波非线性增强,植物分布密度和分布宽度对堤顶前段水流厚度的影响也随之增强,而对堤顶后段水流厚度的影响则减弱,且堤顶后缘水流厚度约为堤顶前缘厚度的二分之一;在波浪非线性较大情况下,植物的存在对堤顶流速度的空间分布趋势几乎没有影响,但相对堤顶流速度增加程度均大于无植物情况,且堤顶后缘水流速度约为堤顶前缘的1.6倍。

Numerical investigation on effects of emergent rigid vegetation patch on hydrodynamic characteristics of seawall under tsunami wave

To study the effects of emergent rigid vegetation patch on the hydrodynamic characteristics of seawall under the impact of tsunami wave, a high-resolution numerical wave tank is established based on one-phase nonhydrostatic flow model NHWAVE. The computational capability of the numerical model has been calibrated in solitary wave propagating emergent rigid vegetation patch and breaking solitary wave transforming on the seawall. Effects of some prominent factors, such as incident wave height, vegetation density and width on the hydrodynamic characteristics of seawall, have been systematically discussed. Results indicate that the wave energy attenuation rate increases with incident wave height, vegetation density and width. Overtopping layer thickness and flow velocity on the crest of the seawall vary monotonically with the vegetation density and width. As wave nonlinearity increases, influences of vegetation density and width on the overtopping layer thickness are gradually enhanced at the frontal side of the seawall, but weaken at the rear side. The overtopping layer thickness on the rear side of the crest is almost 0.5 times of the frontal side. For large incident wave height, although the influences of vegetation on the velocity distribution of overtopping flow is limited, the current velocity is greater than that without vegetation. Meanwhile, the magnitude of the current velocity on the rear side of the crest is about 1.6 times of the frontal side.