INTERNATIONAL JOURNAL OF RESEARCH IN AERONAUTICAL AND MECHANICAL ENGINEERING ISSN (ONLINE): 2321-3051 Vol.3 Issue.1, January 2015. Pgs: 104-118 Nidhul K, Sunil A S, Kishore V 104 Numerical Investigation of Flow Characteristics over a Square Cylinder with a Detached Flat Plate of Varying Thickness at Critical Gap Distance in the wake at Low Reynolds Number Nidhul K 1 , Sunil A S 2 , Kishore V 3 PG student, Govt. Engineering College Thrissur, nidhul07@gmail.com 1 Associate Professor, Govt. Engineering College Thrissur, sunilkoni@gmail.com 2 Assistant Professor, Govt. Engineering College Kannur, kish.venugopal@gmail.com 3 Abstract Flow past a square cylinder with and without corner modifications is carried out numerically by using CFD fluent. The wake is generated by a uniform flow of Reynolds number (Re) 150 based on the characteristic length of the cylinder, D. 2D unsteady numerical simulation is done using FVM employing pressure based solver and PISO scheme. A computational grid independence study has been done to obtain a grid resolution which predicts the results without any discrepancies. The flow separation point for the square cylinder with and without corner modifications is obtained. The pressure distribution in the near wake region and around the square cylinder surface is also investigated for different corner geometries. The results are presented in the form of coefficient of pressure Vs Domain length/D, Coefficient of pressure along the cylinder wall and wall shear stress along the cylinder wall. The results indicate that the flow separation in case of square cylinder without sharp corners is delayed. The adverse pressure gradient along the surface of the cylinder and in the near wake region is smaller for round corners. The tangential velocity of square cylinder with sharp corners is large when compared with modified corners. Keywords: Square Cylinder, Corner modifications, Reynolds number, wake, grid independence, flow separation point, Pressure distribution, Lift coefficient, Drag coefficient. . 1. Introduction Vortex shedding behind bluff bodies is of concern for many engineering applications. Bluff bodies are structures with shapes that significantly disturb the flow around them, as opposed to flow around a streamlined body. Fluid flow past a cylindrical object generates vorticity when Re is increased due to the shear present in the boundary layer. This vorticity in the flow field coalesces into regions of concentrated vorticity known as vortices. Further increase of the Reynolds number (Re > 40) makes the steady vortices to become unstable and the flow bifurcates to a time-periodic state, in which opposite-signed vortices are periodically shed from the opposite sides of the near wake; this is known as the primary instability of the wake. The periodic vortex shedding generates oscillatory forces on the cylinder. The forces on the plane of the cross-section of the cylinder can be decomposed into drag– the force acting in the same direction of the free-stream – and lift – the force