Computation of three-dimensional flow around square and circular piers

The aim of the present study is to investigate, by numerical simulation, th e three-dimensional turbulent flow field around square and circular piers. The numerical model employs a finite volume method based on MacCormack's ex plicit predictor-corrector scheme to solve weakly compressible hydrodynamic equations for turbulent flow. Computed results are compared with Dargahi"s experimental measurements to assess the validity of the proposed model. Ve ry good agreements are obtained. The results of flow simulation indicate th at near the upstream face of the pier there exists a downflow, which joins the separated flow to form the horseshoe vortex stretched around the pier. This horseshoe vortex interacts with the wake vortex to create the upflow b ehind the pier. These phenomena appear to be very important to the mechanis m of scouring around the pier. In general, the flow patterns for the square and circular piers are similar. However, the strengths of the downflow and horseshoe vortex are greater in the case of the square pier. The position of the horseshoe vortex around the circular pier is closer to the front fac e than that around the square pier. In the meantime, the domain of the wake flow in the case of the square pier is greater than that in the case of th e circular one. Copyright (C) 2000 John Wiley & Sons, Ltd.