Poiseuille flow across an eccentrically confined stationary/rotating cylinder

Effect of eccentricity-ratio and rotation on a Poiseuille flow across a stationary/rotating cylinder is studied numerically for various Reynolds number (Re=50-150) at a blockage ratio of β=20%. Several interesting flow-patterns and flow-transition, for various eccentricity-ratio (−75%≤γ≤+75%) and rotational-velocity (0≤α≤2) at Re=100 are noted. The flow patterns are understood with the help of streamlines and vorticity contours. The ensuing flow is analyzed with the help of separation point on the surface of the cylinder, strength and trajectory of the shed-vortices and flow distribution above and below the cylinder. Flow-transition from unsteady to steady flow is reported as a flow-regime map, at various values of α and γ. Stabilization effect is more at positive as compared to negative eccentricity, for counter clockwise (CCW) rotating cylinder. It is established that the mechanism of flow-stabilization is different for positive and negative eccentricity, for rotating cylinder. For stationary cylinder, increase in eccentricity causes a reduction in the drag-coefficient and Strouhal-number; and a change in the direction of lift force at higher eccentricity ratio. Under the influence of rotation, a reduction (enhancement) in the drag-force is obtained at a constant positive (negative) eccentricity. Stabilization effect of rotation and eccentricity can be used for flow control.