Large-scale dynamos at high Rm: do they work and can we get a statistical theory?

Steve Tobias
University of Leeds

In this talk I will discuss the generation of large-scale magnetic fields in astrophysical objects such as the Sun. I will focus on the mechanisms that lead to this generation and consider the circumstances under which these mechanisms are not swamped by the dynamo's natural inclination to produce fluctuations at the resistive scale. I will argue that mean responses will lead to the production of large-scale fields providing the small-scales are suppressed, and it may be more fruitful to seek mechanisms that suppress fluctuations (i.e. narrow the distributions of statistical properties of the turbulence) rather than those that boost the mean of the distributions. I will conclude by speculating whether this behaviour might be captured by the recently developed technique of Direct Statistical Simulation.

Presentation (PDF File)

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