双排立柱结构附近孤立波传播变形数值模拟

Study on the Solitary Wave Transformation around the Vertical Double-Row of Piles

基于Navier-Stokes方程运用大涡模拟建立了三维数值波浪水槽,分别模拟了孤立波与并列和交错两种双排立柱结构的相互作用的过程,并通过物理模型实验对比验证了双排立柱结构附近的自由液面、流速和动水压强的变化特征.随后运用校核的模型进一步分析了双排立柱结构附近波浪的反射系数、透射系数、能量耗散系数以及能量耗散系数与拖曳力系数之间的关系,并考虑了不同入射波高和柱间间隙的影响.研究结果表明:并列和交错两种双排立柱结构附近孤立波传播变形的特征总体变化趋势相似:随着圆心距与圆柱直径的比值(间隙比)增大,反射系数和能量耗散系数减小,透射系数增大;随着入射波高与静水深比值(相对入射波高)增大,孤立波的反射系数变化较小且无规则,而透射系数逐渐减小,能量耗散系数逐渐增大;并列双排立柱结构附近的波浪的透射系数大于交错双排立柱结构,而反射系数则小于交错双排柱结构,当间隙比大于2.0时,布置方式对孤立波传播变形的影响可以忽略不计.最后通过回归分析发现两种布置双排立柱结构的平均拖曳力系数与能量耗散系数均存在线性关系.

A numerical wave tank based on the Navier-Stokes equations with Large Eddy Simulation(LES) turbulence closure was developed to reproduce the interaction between the solitary wave and a double-row of piles with tandem and staggered arrangement,respectively.The numerical model was firstly validated by our laboratory experiments in view of free-surface elevations,velocities and dynamic pressures near the pile structure.The validated model was then used to analyze wave reflection,wave transmission,energy dissipation around the piles as well as the relationship between energy dissipation coefficient and drag coefficient,the effects of both incident wave height and spacing between adjacent piles were also examined.Results show that the wave transformation characteristics are similar for both arrangements of the double-row of vertical piles.As the ratio of center spacing between piles to pile diameter increases,both the reflection coefficient and the energy dissipation coefficient decrease while the transmission coefficient increases.When the ratio of incident wave height to still water level increases,the variation of reflection coefficient is small and erratic but the transmission coefficient deceases slowly and the energy dissipation coefficient increases slightly.The staggered arrangement has a larger reflection coefficient and a smaller transmission coefficient compared to the tandem arrangement.When the ratio of center spacing between piles to pile diameter is greater than 2.0,the effect of pile arrangement on solitary wave transformation becomes insignificant.Finally,a linear relationship between the wave dissipation coefficient and the mean drag coefficient of the two-row of piles is proposed via regression analysis.