GENERATION OF A SYMMETRIC MAGNETIC FIELD BY THERMAL CONVECTION IN A PLANE ROTATING LAYER

We investigate numerically magnetic field generation by thermal convection with swim periodicity cells in a rotating horizontal layer of an electrically conducting fluid with stress-free electrically perfectly conducting boundaries for Rayleigh numbers in the interval 5100 <= Re <= 5800 Dynamos of three kinds, apparently not encountered before, ale presented (i) Steady and time-periodic regimes, where the flow and magnetic field ale symmetric abouta vertical axis In regimes with this symmetry, the global alpha-effect is insignificant, and the complex structure of the system of amplitude equations controlling weakly non-linear stability of the system to perturbations with large spatial and temporal scales suggests that. the perturbations are likely to exhibit uncommon complex patterns of behaviour, to be studied in the future work (ii) Periodic in time regimes, where the magnetic field is always concentrated in the interior of the convective layer in contrast to the behaviour first observed by St Pierre (1993) and often perceived as genetic for electrically infinitely conducting boundaries (iii) A dynamo exhibiting chaotic behaviour of heteroclinic nature, where a sample trajectory enjoys excursions between a. periodic magnetohydrodynamic regime and rolls The rolls are amagnetic, but generate magnetic fields kinematically As a Jesuit, magnetic energy reduces almost to zero, while the rolls are approached