后台阶下游床面冲刷过程数值模拟研究  

Numerical Investigation on the local scour at the downstream of the backward-facing step flow

作　　者：刘春嵘[1] 呼和敖德[2] 

机构地区：[1]湖南大学力学与航空航天学院,湖南长沙410082 [2]中国科学院力学研究所,北京100080

出　　处：《海洋工程》2008年第1期51-56,共6页The Ocean Engineering

基　　金：国家自然科学基金资助项目(10602017)

摘　　要：以床面瞬时剪应力作为泥沙起动及输运的水动力机制,建立了结构物周围复杂流场下床面局部冲刷的数学模型。并应用大涡模拟方法对后台阶下游三维湍流流动进行数值模拟,得到台阶下游床面瞬时剪应力的分布规律。为了确定床面瞬时剪应力与泥沙上扬通量的关系,先应用数学模型对不同模型参数下,冲刷开始后5分钟时台阶下游床面形状进行试算。通过试算与实验结果的比较,确定床面瞬时剪应力与泥沙上扬通量关系中需要的模型参数。进一步对冲刷开始后30分钟内台阶下游床面演化规律进行模拟,模拟结果与实验结果相符合。Assuming that the instantaneous bed shear stress is the hydrodynamic mechanism of sediment incipience and transportation, the numerical model of the local scour under the complex flows around the structures is presented. The method of large eddy simulation is employed to simulate the three dimensional turbulence at the downstream of the backward-facing step flow, and the distribution of the instantaneous bed shear stress at the downstream of the step is obtained. In order to determine the relation between the pick-up flux and the instantaneous bed shear stress, the formations of the bed at the downstream of the step at 5 minutes after the beginning of the scour are simulated according to different model parameters. The model parameters needed to calculate the pick-up flux are determined by comparing the results of numerical simulation and experiment. The process of the scour at the downstream of the step during 30 minutes after the beginning of the scour is simulated, and the results of the simulation and the experiment agree well.

关 键 词：局部冲刷 泥沙起动 后台阶流 大涡模拟 瞬时剪应力 

分 类 号：TV142[水利工程—水力学及河流动力学]