Computational unsteady flow dynamics: oscillating flow about a circular cylinder.

Abstract

The numerical experiments, carried out through the use of the vorticity-stream function equations and their finite difference form, on co-existing flows sinusoidal or non-sinusoidal oscillation plus steady mean flow) are described. A third-order in time, second-order in space, three-level predictor-corrector finite-difference scheme has been used. The Poisson equation for the stream function was solved by a Fast Poisson Solver based on the High Order Difference Approximation with Identity Expansion (HODIE) and the Fast Fourier Transform (FFT) methods provided by the IMSL mathematical library. The results have revealed, for the first time, the existence of a very interesting wake comprised of three rows of heterostrophic vortices at certain Keulegan-Carpenter numbers and relative current ratios. The existence of such a street has been vindicated by physical experiments.