Flow past a circular cylinder in the vicinity of a plane wall

Results have been reported here for flow past a stationary cylinder in the vicinity of a solid wall. Navier-Stokes equations are solved here in stream-function/vorticity formulation using an improved overset grid method while using a very high spectral accuracy compact scheme to represent the convection process. To study the effect of changing the gap (G) between the cylinder (of diameter D) and the wall, lift and drag coefficients are obtained for (a) an intermediate gap ratio of G/D = 0.5 and (b) a larger gap ratio of G/D = 1.5. Computed results are compared with flow visualization results of Price et al. for Re = 1200 only. This problem can be viewed as one of vortex-induced instability problem where the instability arises due to mutual interaction of the vorticity field associated with the plane wall boundary layer and the vortices that are created on the cylinder surface that are shed subsequently. Such an instability mechanism was introduced in Sengupta et al. (2003a) and the flow behaviour in the present case is explained via vorticity dynamics and the developed by-pass instability theory of Sengupta et al. (c) 2005 Elsevier Ltd. All rights reserved.