The experiments described in this paper were designed to clarify the effect of velocity gradient on the flow about a circular cylinder in cross linear shear flow with fovario velocity gradients at Reynolds numbers in the range of 2.67×10
3 to 1.07×10
4.
Pressure distributions around the cylinder, separation points of both sides of the cylinder, the shapes of shear layer around the cylinder and the vorticities in it are unsymmetrical in the shear flow.
The interaction between the velocity gradient of main flow and the vorticity of the boundary layer on the cylinder and displacement effect is responsible for these unsymmetry.
The lift is acted on the cylinder as a result of unsymmetrical pressure distribution and increases with increasing velocity gradient. The pressure drag acting on the cylinder is chiefly affected not by the velocity gradient but by the turbulence in main flow.
The position of separation point is shifted toward downstream on the higher velocity side, on the other hand toward upstream on the lower velocity side.
Shear layer on the lower velocity side is slightly thicker than on the higher and vorticity is greater in the higher velocity side than in the lower.
With an increases of velocity gradient, the transition point approaches to the cylinder and the periodicity of fluctuation in the shear layer decays.
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