Flow around a circular cylinder in linear shear flows at subcritical Reynolds number

摘要

Vortex shedding and aerodynamic forces around a circular cylinder in linear shear flows with its axis normal to the plane of the velocity shear profile are investigated numerically and experimentally at subcritical Reynolds number. Large eddy simulation using a dynamic Smagorinsky subgrid model is performed to supply physical explanations of the flow phenomena. The shear parameter beta, which is based on the velocity gradient, cylinder diameter and upstream mean velocity at the center plane of the cylinder, varies from 0 to 0.27. It is found that the Strouhal number shows no significant variation with shear parameter. The stagnation point shifts to the high-velocity side and it greatly influences the aerodynamic force acting oil the cylinder. There is a lift force due to the asymmetrical distribution of pressure around the cylinder, and it acts from the high-velocity side to the low-velocity side at subcritical Reynolds number.