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Vortex interactions and mixing in large Atwood number two-dimensional turbulence

Joly, Laurent and Reinaud, Jean and Fontane, Jérôme Vortex interactions and mixing in large Atwood number two-dimensional turbulence. (2010) In: 63rd Annual Meeting of the American Physical Society's Division of Fluid Dynamics (DFD) , 21-23 Nov 2010, Long Beach, United States .

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Official URL: http://meetings.aps.org/link/BAPS.2010.DFD.LA.2

Abstract

We perform direct numerical simulations of the relaxation of variable-density two-dimensional turbulence. An initial collection of vortices is evolved in time together with an initially bimodal density field corresponding to an Atwood number A = 2/3. The initial vortex collection counts a thousand Gaussian vortices and spans a radius decade. The vortex Reynolds number of the smaller ones Γ/ν = 300 and we consider a unit Schmidt number. The misaligned density-gradient and fluid acceleration trigger baroclinic sources and sinks of vorticity on density fronts. The adaptive spatial resolution increase up to 6144² at peak enstrophy production time. We analyze the bias on both the evolution of the vortex population (number and radii) and the mixing progress, against a passive scalar reference simulation started from the same initial fields. Vortex carrying high-density fluid are mass-depleted or break-up into filamentary debris rapidly removed by mass diffusion. Meanwhile, intense vortices merge and trap almost unmixed low-density fluid. The resulting density field is negatively skewed and the mass exchange between vortices and the interlacing medium is shown to be the result of vortex interactions of different types among which asymmetric binary interactions are playing a central role in the mass-segregation by vorticity.

Item Type:Conference or Workshop Item (Lecture)
Additional Information:63rd Annual Meeting of the American Physical Society, Division of Fluid Dynamics (DFD), Bulletin APS Series II, Vol. 55, No. 16, ISSN: 0003-0503, 21-23 November, Long Beach USA.
Audience (conference):International conference without published proceedings
Uncontrolled Keywords:
Institution: Université de Toulouse > Institut Supérieur de l'Aéronautique et de l'Espace - ISAE
Other partners > University of St Andrews (UNITED KINGDOM)
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Deposited By:Laurent JOLY

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