速度剪切流中圆柱体绕流特性的数值模拟

采用由速度梯度、圆柱半径以及圆柱中心平面上的来流平均速度定义的无量纲剪切参数β来描述速度剪切的强度。在雷诺数Re=60-1000范围内，运用三维直接数值模拟(DNS)和大涡模拟(LES)两种方法对速度剪切流中的圆柱体的绕流特性进行了数值模拟。研究了驻点、高速和低速两侧分离点、圆柱表面压力分布以及不稳定尾流结构随剪切参数的变化及其对雷诺数的依赖性，从而得到了剪切流中圆柱体的气动力以及脱落特性，并对其机理进行了详细探讨。

Numerical analysis of aerodynamic forces on circular cylinder in linear shear flow

Three-dimensional direct numerical simulation(DNS) and large eddy simulation(LES) were performed to investigate aerodynamic forces on a circular cylinder in linear shear flow at Reynolds number of Re=60~1 000.The shear parameter β,which is based on the velocity gradient,cylinder diameter and upstream mean velocity at the center plane of the cylinder,varies from 0 to 0.30.The changes of the stagnation point,separation points,and lift coefficients with the variation of shear parameter were studied.The results show that the stagnation point moves to the high-velocity side almost linearly with shear parameter,which mainly influences the aerodynamic forces acting on a circular cylinder in shear flow.Both the Reynolds number and shear parameter influence the movement of the stagnation point and separation point.The lift force increases with the increase of shear parameter and at the same time from the high-velocity side to the low-velocity side.