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

Description/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.