Three-dimensional instability during vortex merging
نویسندگان
چکیده
The interaction of two parallel vortices of equal circulation is observed experimentally. For low Reynolds numbers (Re), the vortices remain two-dimensional and merge into a single one, when their time-dependent core size exceeds approximately 30% of the vortex separation distance. At higher Re, a three-dimensional instability is discovered, showing the characteristics of an elliptic instability of the vortex cores. The instability rapidly generates small-scale turbulent motion, which initiates merging for smaller core sizes and produces a bigger nal vortex than for laminar
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