Characteristics of two-dimensional flow around a rotating circular cylinder near a plane wall

We simulate a two-dimensional incompressible flow around a rotating circular cylinder near a plane wall at the Reynolds number Re=200 by using the lattice Boltzmann equation with multiple relaxation times. We investigate the flow pattern in the parameter space of the rotational rate γ≔ωa∕U and the normalized gap h≔H∕D, where ω is the angular velocity of the cylinder, a and D are the cylinder radius and diameter, respectively, U is the inflow velocity, and H is the gap between the cylinder and the wall. We quantify the effects of γ and h on the hydrodynamic forces and the frequency of vortex shedding from the cylinder. Our results indicate that two critical values of h, hdown and hup, exist, which depend on γ. The flow is steady when h hup. When hdown 0, C¯D is no longer a monotonic function of h. The mean drag coefficient C¯D varies significantly in the range hdown hup, the wall effect diminishes.