Inviscid Model of Two-Dimensional Vortex Shedding by a Circular Cylinder

Abstract

A discrete vortex model based on potential flow and boundary-layer interaction, rediscretization of shear layers, and circulation dissipation is developed to determine the characteristics of an impulsively started flow about a circular cylinder. The evolution of the flow from the start to very large times, lift and drag forces, Strouhal number, oscillations of the separation and stagnation points, and the vortex-street characteristics are calculated and compared with experiments. b CD CL Cpb c D fv h / j m N n q Re St s ds t At U u v w z F 7 6 X v p Nomenclature = longitudinal spacing of vortices = drag coefficient = lift coefficient = base pressure coefficient = radius of the cylinder - diameter of the cylinder ,D = 2c = vortex shedding frequency = transverse spacing of vortices = an index = distance to nascent vortex from cylinder = number of vortices on a sheet = an index = total velocity at a point = Reynolds number, UD/v = Strouhal number, fvD/ U = distance along a sheet = point vortex spacing = time or Ut/c for U= 1 and c = 1 - numerical step size = velocity of the ambient flow = x component of velocity -y component of velocity = complex velocity potential = complex variable = circulation = circulation per unit length = angle measured from ( - c,0) = dissipation parameter = kinematic viscosity of fluid = density of fluid = vorticity