Flow dynamics in the turbulent wake of a sphere at sub-critical Reynolds numbers

Direct numerical simulations of the flow over a sphere have been performed. The computations have been carried out in the sub-critical regime at Re = 3700 and Re = 10,000 (based on the free-stream velocity and the sphere diameter). A parallel unstructured symmetry-preserving formulation has been used for simulating the flow. Computations have been carried out on unstructured grids obtained by the constant-step rotation about the axis of a two-dimensional grid. With this discretisation, the Poisson equation has been solved by means of a Fourier diagonalization method. Particular attention has been devoted to investigate the shear-layer instabilities and its influence in the vortical structures, as well as the wake configuration. The main features of the flow including power spectra of a set of selected monitoring probes at different positions have been described and discussed in detail. Detailed information about turbulent statistics have also been provided. (c) 2012 Elsevier Ltd. All rights reserved.