Simulation of vortex-shedding flows using high-order fractional step methods
by
Michael Kirkpatrick
The University of Sydney
Coauthors: Steven Armfield, John Kent, Terry Dixon (Sugar Research Institute)

Unsteady flow past a square cylinder is simulated using a fractional step method to advance the Navier-Stokes equations in time. The fractional step method is a single step method whereby the momentum equations are solved using an explicit/implicit scheme and an approximate pressure field to yield an estimate of the velocity. This velocity is then projected onto a divergence free field using a pressure correction obtained by the solution of a Poisson pressure correction equation. The integration then proceeds to the next time step. Results have been obtained using a hybrid Adams-Bashforth/Crank-Nicolson scheme and second order in time behaviour is verified for velocities for a start-up flow over a square cylinder. A higher order Runge-Kutta scheme has also been developed and is being validated for the same start-up flow. Results will be presented demonstrating the efficiency of fractional step methods for unsteady flows of this type, as well as detailing some of the pitfalls that can be encountered with this approach.

Date received: August 11, 1999