Direct numerical simulation of flow past elliptic cylinders

Flow over elliptic cylinders can be considered prototypical of flow over a range of bluff bodies since the geometry allows one to study the effect of both thickness and angle-of-attack on the flow field. Therefore, a careful study of this flow should provide valuable insight into the phenomenon of unsteady separation and the structure of bluff body wakes. with this in mind, a spectral collocation technique has been developed to simulate the full three-dimensional incompressible flow over elliptic cylinders and, unlike spectral element and spectral multidomain techniques, here the flow is solved in a single domain. The equations are discretized on a body-fitted elliptic cylindrical grid and properties of the metric associated with this coordinate system are used to solve the governing equations in an efficient manner. Key issues including the inflow and outflow boundary conditions and time-discretization are discussed in detail with the hope that this will facilitate future simulations of similar flows. Finally, we present results of two- and three-dimensional simulations for a range of flow and geometric parameters. The results are compared with available experimental data and it is found that important quantities like Strouhal numbers and drag coefficients match well with established values. (C) 1996 Academic Press, Inc.