Numerical Simulations of Inhomogeneous Turbulence Generated by an Oscillating Grid and Submitted to Solid-Body Rotation

Abstract

An experiment made by Hopfinger et al., 1982 (hereafter referred to as HBG),shows how a turbulence,generated by an oscillating grid in a rotating tank, is affected by rotation for various values of the Rossby number. Near the grid,the Rossby number is set to a large value so that the flow is unaffected by rotation. An abrupt transition is located at a distance from the grid corresponding to a local Rossby number of about 0.20. Then, the flow, which becomes dominated by rotation, consists of concentrated vortices having axes of rotation approximately parallel to the rotation axis but a pure two-dimensional state is not reached. This kind of experiment is of great interest in geophysical applications because the transition between a three-dimensional small scale turbulence to a quasi two-dimensional one with larger characteristic scale is observed in atmospheric or oceanic flows, but not completely understood. Furthermore, it should lead us to a better understanding of cyclones genesis.