Effect of blockage ratio on wake transition for flow past square cylinder

Two-dimensional numerical investigations are carried out to study the behavior of wake transition for flow past square cylinder confined between two parallel walls. It is known from past literature that nature of wall confinement affects the behavior of vortex shedding behind the obstacle. The present work reports dependence of the critical Reynolds number (Re-cr) for onset of planar vortex shedding on blockage ratio. The effect of wall confinement on characteristic features of the wake, such as wake bubble size and shear layer behavior has been studied. The characteristic relationship between Strouhal number and flow Reynolds number has been presented for different values of blockage ratios. The temporal characteristics of the wake are presented. (C) 2008 The Japan Society of Fluid Mechanics and Elsevier B.V. All rights reserved.