Spanwise vorticity at the centerplane of a sphere at Re=10,000

This image shows the evolution of the spanwise vorticity at the centerplane in the wake of a towed sphere. In this region of the flow, stratification effects are minimal. The simulation was performed using large eddy simulation (LES) with a Reynolds number of 10,000, a Froude number of 3, and a Prandtl number of 1. Here we can see the formation of Kelvin-Helmholtz rollers in the separated shear layers and the small scale structures at the back of the recirculating region. The black square indicates a probe location where we measure the time history of the flow to analyze the frequency of various instabilities.