UNSTEADY NUMERICAL ANALYSIS OF FLOW ACROSS 2D CYLINDER

2-D computational analyses were conducted for unsteady viscous flow across cylinders of different geometries and different incident angle. Circular, square and elliptic (both at 0 degrees and 90 degrees angles of incidence) cylinders were examined. The calculations were performed by solving the unsteady 2-D Navier-Stokes equation at Re = 100. The calculated results produce drag and lift coefficients, as well as Strouhal number in excellent agreement with published data. Calculations for unsteady, incompressible 2D flow around a square cylinder at incidence angle of 0 degrees and 45 degrees and for Reynolds number = 100 were carried out. Cycle independence and grid independence results were obtained for the Strouhal number. The results were in excellent agreement with the available experimental and numerical results. Numerical results show that the Strouhal number increases with fluid angle of incidence on the cylinder. The wake behind the cylinder is wider and more violent for a square cylinder at 45 degrees incidence compared to a square at 0 degrees this is due to the increase in the characteristic length in the flow direction. The Strouhal number is highest for elliptic geometry among all cylinders in this research. For the geometries elliptic at 0 degrees at Re = 100, there is not vortex shedding behind the cylinder. This is due to dominance of inertia forces over viscous forces. The present study was carried out for a 2-D single cylinder at fixed location inside a channel for unidirectional velocity. To get more accurate results computation on 3-D geometry should be carried out.