# HRT

## Seminar

### Slow temporal scales in the dynamics of vortices at large Reynolds numbers in a cylindrical experiment

Burguete, J (Navarra)
Friday 12 September 2008, 09:20-09:40

Seminar Room 1, Newton Institute

#### Abstract

We present results concerning an experimental setup where a fluid is stirred in a cylindrical cavity up to a Reynolds number of $10^6$. We show that the averaged velocity field of the turbulent flow bifurcates subcritically breaking some symmetries of the problem and becomes time-dependent because of equatorial vortices moving with a precession movement. This subcriticality produces a bistable regime, whose main characteristics are successfully reproduced using a three well potential model with additive noise. We characterized the hysteresis region, not previously observed, in this bifurcation. This hysteresis appears only for a extremely small range of parameters. Three different time-scales are relevant to the dynamics, two of them very slow compared to the impeller frequency.

#### Video

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