Direct Numerical Simulation of Flow Past Elliptic Cylinders

number [4] or flows at early times after an impulsive start [5]. Experimental techniques have become very sophistiFlow over elliptic cylinders can be considered prototypical of flow over a range of bluff bodies since the geometry allows one to study cated in recent years but an extensive spatial and temporal the effect of both thickness and angle-of-attack on the flow field. analysis of the three-dimensional (3D) flow field would Therefore, a careful study of this flow should provide valuable inquickly overwhelm the available resources. Numerical simsight into the phenomenon of unsteady separation and the structure ulations provide a promising approach to analyzing this of bluff body wakes. With this in mind, a spectral collocation techproblem. However, there remain a number of issues that nique has been developed to simulate the full three-dimensional need to be addressed, namely intelligent grid generation, incompressible flow over elliptic cylinders and, unlike spectral element and spectral multidomain techniques, here the flow is solved efficient solution of the governing equations, and the ability in a single domain. The equations are discretized on a body-fitted to interpret the gigabytes of data that would be generated elliptic cylindrical grid and properties of the metric associated with from the simulations. this coordinate system are used to solve the governing equations Here we consider elliptic cylinders which are more genin an efficient manner. Key issues including the inflow and outflow eral geometrical configurations than the canonical circular boundary conditions and time-discretization are discussed in detail with the hope that this will facilitate future simulations of similar cylinder and provide a richer flow behavior characteristic flows. Finally, we present results of twoand three-dimensional of typical engineering flow configurations. For these cylinsimulations for a range of flow and geometric parameters. The ders, changes in eccentricity allow for shapes ranging from results are compared with available experimental data and it is that of a circular cylinder to a flat plate. There have been found that important quantities like Strouhal numbers and drag a few numerical simulations of flows over elliptic cylinders. coefficients match well with established values. Q 1996 Academic