DIRECT NUMERICAL-SIMULATION OF FLOW PAST ELLIPTIC CYLINDERS

Flow over elliptic cylinders can be considered prototypical of flow ov er 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. Theref ore, 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 d eveloped to simulate the full three-dimensional incompressible flow ov er elliptic cylinders and, unlike spectral element and spectral multid omain techniques, here the flow is solved in a single domain. The equa tions are discretized on a body-fitted elliptic cylindrical grid and p roperties of the metric associated with this coordinate system are use d to solve the governing equations in an efficient manner. Key issues including the inflow and outflow boundary conditions and time-discreti zation are discussed in detail with the hope that this will facilitate future simulations of similar flows. Finally, we present results of t wo- and three-dimensional simulations for a range of flow and geometri c parameters. The results are compared with available experimental dat a and it is found that important quantities like Strouhal numbers and drag coefficients match well with established values. (C) 1996 Academi c Press, Inc.