Detached-eddy simulation of flow around a circular cylinder in ground effect

Abstract

In this study we performed a detached-eddy simulation (DES) of flow around a circular cylinder placed near and parallel to a moving ground, on which no boundary layer developed to interfere with the cylinder. The results were compared with experiments previously reported by the authors, and also with two-dimensional unsteady RANS computations. The DES correctly predicted the cessation of the Kármán-type vortex shedding behind the cylinder, whereas the unsteady RANS also predicted it but at a much smaller ‘gap ratio’ (i.e. the ratio of the gap between the cylinder and the ground, h, to the cylinder diameter d) compared with the experiments. Time-averaged force coefficients, separation angles and velocity profiles in the near wake region predicted by the DES were in good agreement with the experiments. The major features of instantaneous wake structures were well reproduced in both large- and small-gap regimes, and also in the intermediate-gap regime, where the DES predicted a temporary formation of a small dead-fluid zone behind the cylinder.

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