考虑水平隐蔽度影响的卵石周围水流结构分析

Analysis of flow structure around pebbles considering horizontal hidden degree

基于二维数值水槽，在高雷诺数Re=5×10^4～20X10^6条件下，从卵石在床面不同排列方式下单颗粒到多颗粒圆状卵石的位置及受力情况的角度出发，综合考虑水平与竖直两个方向定义的隐蔽度，颗粒起动采用滚动模式，结合水流结构，进一步探讨其起动规律，亦对沙卵石河床冲刷和粗化的研究提供基础。通过比较9种情况下阻力与升力的数值结果分析表明，水平隐蔽度对水动力因素亦有较大影响，阻力系数随着相对水平隐蔽度的增大先减小后增大，经综合考虑其更符合真实情况，最后对附近作用区域涡量分布的影响进行了讨论。

Two-dimensional fluid computations are performed to investigate the flows around one or more circu lar pebbles in meticulous arrangements at high Reynolds number, Re = 5 x 10^4 - 20 x 10^4, which gives consideration to hidden degree in the horizontal and vertical direction. The rolling model combined with water flow structure is adopted to further explore the incipient rule of particles. Foundation of future research about scouring and coarsening of pebbles bed is laid in the paper. Comparison of numerical results shows that the horizontal hidden degree has a relatively high effect on hydrodynamic forces factors in 9 cases, and the drag coefficients decrease first and then increase along with the increase of relative horizontal hidden degree, which t, are more accordant with the actual conditions. Finally, the effects of the vortices near pebbles on the fluid- dynamic forces acting on the region are discussed.