The Lorentz force effect on the On-Off dynamo intermittency
Abstract
An investigation of the dynamo instability close to the threshold produced by an ABC forced flow is presented. We focus on the on-off intermittency behavior of the dynamo and the counter-effect of the Lorentz force in the non-linear stage of the dynamo. The Lorentz force drastically alters the statistics of the turbulent fluctuations of the flow and reduces their amplitude. As a result much longer burst (on-phases) are observed than what is expected based on the amplitude of the fluctuations in the kinematic regime of the dynamo. For large Reynolds numbers, the duration time of the ``On'' phase follows a power law distribution, while for smaller Reynolds numbers the Lorentz force completely kills the noise and the system transits from a chaotic state into a ``laminar'' time periodic flow. The behavior of the On-Off intermittency as the Reynolds number is increased is also examined. The connections with dynamo experiments and theoretical modeling are discussed.
Cite
@article{arxiv.0710.0063,
title = {The Lorentz force effect on the On-Off dynamo intermittency},
author = {Alexandros Alexakis and Yannick Ponty},
journal= {arXiv preprint arXiv:0710.0063},
year = {2007}
}
Comments
8 pages