Direct numerical simulation of a spatially evolving flow from an asymmetric wake to a mixing layer
Résumé
In this paper, the flow obtained behind a trailing edge separating two streams of different velocities is studied by means of direct numerical simulation. The influence of the shape of the trailing edge, that can be either blunt or bevelled, is considered through the analysis of the destabilizing mechanisms and their resulting effects on the spatial development of the flow. It is shown that the use of a bevelled trailing edge leads to a conventional mixing-layer dynamics with moderate effects of the wake component. In contrast, a self-excited flow is obtained behind a blunt trailing edge where usual features of the wake dynamics are recovered. In terms of receptivity, it is found that the flow behind a bevelled trailing edge is strongly sensitive to upstream perturbations. The inverse behaviour is observed for the flow behind a blunt trailing edge. These differences are interpreted in terms of convective/absolute stability. The vortical organization obtained in each case is discussed using vorticity visualization.