为了降低钝体绕流的阻力，以圆柱为研究对象，考虑在圆柱表面布置沟槽来实现减阻。研究采用大涡模拟（Large Eddy Simulation，LES）方法对雷诺数Re为3 900的圆柱绕流进行数值模拟，通过表面沟槽影响近壁区流动来达到流动控制的效果。分析了V型和L型两种沟槽分别以横向和纵向形式布置时对圆柱阻力系数的影响，通过对比粗糙圆柱与光滑圆柱的壁面摩擦力系数〖JP2〗、流动分离点及近壁区流场结构，研究了表面沟槽对于钝体流动的减阻机理。数值模拟结果表明：表面布置特定深度与间距的沟槽后，粗糙圆柱的阻力系数与光滑圆柱相比最多可降低12.5%，边界层分离点也更延后；流体在流经沟槽表面时，会在沟槽底部形成稳定的旋转小涡，减少了壁面摩擦阻力。

In order to reduce the drag of bluff bodies, a circular cylinder was selected as the research object and riblets were applied to the cylinder surface. Flow over a circular cylinder at Re=3 900 was simulated numerically using the large eddy simulation (LES) method. The effective flow control was achieved using surface riblets under its influence to the nearwall flow. The influence of Vshaped and Lshaped riblets, which were arranged on the smooth cylinder surface in horizontal and vertical forms, respectively, on the drag coefficient of the cylinder was analyzed and the drag reduction mechanism of the flow over bluff bodies by arranging surface riblets was explored according to the detailed comparison of wall friction coefficient, flow separation point and nearwall flow field structures between the smooth and rough cylinders. The numerical simulation results show that after the riblets with specific depth and spacing are arranged on the surface, the drag coefficient of the rough cylinder can be reduced by up to 12.5% compared with the smooth cylinder, and the separation point of boundary layer is also more rearward; when the fluid flows through the surface of the riblets, a stable rotating vortex will be formed at the bottom of the riblets, which reduces the wall frictional drag.

TK8

上海理工大学学位点引导布局与建设培育项目(XWDA2021104)