浮泥床面桥墩绕流冲刷的数值模拟

Numerical Simulation of Flow around Piers under Fluid Mud Bed

基于Mike 21软件建立了浮泥输移的平面二维数学模型,计算分析了浮泥河床建桥前后的水流流动形态和床面变形状况。结果表明,建桥前后主槽内河床变形均呈单向冲刷变形,岸滩上则以淤积为主;建桥后主槽冲刷能力增强,但增加幅度不大,且冲刷幅度和水深较均匀,与常见沙质河床的冲刷区别较大;桥墩尾流区内水流流速较小,冲刷幅度较小;桥墩纵横向的阻流范围约在2倍椭圆桥墩的长、短轴位置内。

The 2D mathematical model of fluid mud transportation is established based on Mike21 software.The flow and bed deformations before and after the piers construction are computed and analyzed,respectively.The results show that the scouring occurs at the major trough and the silting occurs at the beach before and after the piers construction;after the piers construction,the scouring capability becomes stronger at the major trough but the increased value is little;the scour depth and the water depth become uniform respectively,which differs from those of sand bed;the velocity and the scour depth become little at the wake flow area of piers;The flow-resist area of longitudinal-transverse direction is in the range of two times major-minor axis of elliptic pier.