Uniform-shear flow over a circular cylinder at low Reynolds numbers

The present study has numerically investigated two-dimensional laminar flow over a circular cylinder with uniform planar shear, where the free-stream velocity varies linearly across the cylinder. Numerical simulations using the immersed-boundary method are performed for the ranges of 50⩽Re⩽16050⩽Re⩽160, 0⩽K⩽0.20⩽K⩽0.2, and B=0.1B=0.1 and 0.050.05, where ReRe, K and B are the Reynolds number, the nondimensional shear rate and the blockage ratio, respectively. Results show that the flow depends significantly on the blockage ratio as well as the Reynolds number and shear rate. The vortex-shedding frequency and the mean drag remain nearly constant or slightly decrease with increasing shear rate. On the other hand, the mean lift is exerted from the side of the higher free-stream velocity to that of the lower one, and its magnitude increases linearly in proportion to the shear rate. Flow statistics as well as instantaneous flow fields are presented to identify the characteristics of the uniform-shear flow and then to understand the underlying mechanism.