Anomalous transport in Charney-Hasegawa-Mima flows
Résumé
Transport properties of particles evolving in a system governed by the Charney-Hasegawa-Mima equation are investigated. Transport is found to be anomalous with a non linear evolution of the second moments with time. The origin of this anomaly is traced back to the presence of chaotic jets within the flow. All characteristic transport exponents have a similar value around $\\mu=1.75$, which is also the one found for simple point vortex flows in the literature, indicating some kind of universality. Moreover the law $\\gamma=\\mu+1$ relating the transport exponent to the trapping time exponent within jets is confirmed and an accumulation towards zero of the spectrum of finite time Lyapunov exponent is observed.
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