movie_1vx3d_fix_l1.avi (2.56 MB)

Nonlinear dynamics of the elliptic instability - movie 1

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posted on 2017-01-18, 09:58 authored by Nathanael SchaefferNathanael Schaeffer, Stéphane Le Dizès

Movie 1. Strongly non-linear evolution of the elliptic instability of a single strained Lamb-Oseen vortex (case 1), at Reynolds number Re=Γ/ν=10000 (where Γ is the vortex circulation, ν the kinematic viscosity of the fluid) and in an imposed external strain field of strain rate 0.01, where time scales are normalized by the vortex initial turn-over time. The movie starts with a barely noticeable perturbation, which grows to strong deformations of the vortex core. This instability does not saturate and leads to the appearance of secondary azimuthal structures and the complete breakdown of the vortex. When there is no more vortex core on which to grow, the instability dies and we can see the beginning of a relaminarisation phase at the end of the movie. The total vorticity is equal to 1.0 on the red surface, and the current time t is given in the top right corner in initial vortex turnover time units. See also fig. 5 in the paper.

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elliptic instability vortex non-linear saturation Computational Fluid Dynamics Fluid Physics

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