Numerical simulations of vortices in mixing layers and plane jets

Abstract
Direct numerical simulations of two-dimensional mixing layers and jets are presented first within the temporal approximation, and then with spatial calculations. The evolution of a temperature field as a passive scalar is investigated simultaneously. Besides usual statistical quantities, the results are presented through visualisations of coloured vorticity- and temperature-contours in order to describe the evolutions of the fields with time. Concentrated vortices develop and the evolution of the layer is dominated by the interactions between these eddies which can be viewed as the coherent structures observed in laboratory experiments.