Inviscid Effects of Thin Shear Layers on Four Vortex Systems

The alleviation of the wake vortex hazard by, for example, promoting vortex instability during aircraft landing and takeoff offers the possibility of increased airport capacity for relatively little cost. The interaction of a vortex pair with a thin shear layer using potential flow methods is extended in this paper to shear-layer interactions with more realistic four-vortex systems. Vortex trajectories resulting from encounters with weak and strong shear layers are studied, and the behavior observed is discussed. The effect of the vortex/shear-layer interactions on the robustness of instability mechanisms of four-vortex systems is discussed in relation to the computed trajectories. The computational method enables the salient features of the vortex/shear interactions to be captured in short periods of CPU time using modest processing power. It is concluded that instability mechanisms that utilize the cooperative instability between vortex pairs on either side of the wake are most likely to survive shear-layer interactions. [PUBLICATION ABSTRACT]