Wall-Resolved Large-Eddy Simulation of Flow over a Parametric Set of Gaussian Bumps

Abstract

Wall-resolved large-eddy simulations were carried out for the flow over a parametric set of Gaussian bumps, which are representative of surfaces generating smooth-body separation. The geometry and flow conditions were motivated by an experimental investigation, which was conducted in order to provide data for validating numerical approaches. Because the high-Reynolds-number and three-dimensional shape of the experimental model is challenging, even for approximate numerical techniques, a prior investigation was initiated in order to provide benchmark results that are accessible via wall-resolved large-eddy simulation. It was found that by increasing the bump height, the Reynolds number could be reduced, and flow separation would occur. The modified bump now serves as a surrogate for the original Gaussian bump, producing smooth-body separation. In the present study, solutions are obtained to the unsteady three-dimensional compressible Navier–Stokes equations utilizing a high-fidelity computational scheme and an implicit time-marching approach. A series of simulations is carried out for bumps of varying heights, for both the three-dimensional configuration and a spanwise-periodic subset, corresponding to flow at the midspan. A number of metrics are provided to attest to the accuracy of simulations. Comparisons are made between the spanwise-periodic subset and the three-dimensional configuration, and features of the flowfields are described. The generation of an arch vortex structure evolving about the speed bump geometry is elucidated.