Reversals of a large-scale field generated over a turbulent background - Gallet, B. and Herault, J. and Laroche, C. and Petrelis, F. and Fauve, S.
GEOPHYSICAL AND ASTROPHYSICAL FLUID DYNAMICS 106, 468-492 (2012)
Abstract : We present a study of several systems in which a large-scale field is
generated over a turbulent background. These large-scale fields break a
symmetry of the forcing by selecting a direction. Under certain
conditions, the large-scale field displays reversals so that the
symmetry of the forcing is recovered statistically. We present examples
of such dynamics in the context of the dynamo instability, of
two-dimensional turbulent Kolmogorov flows and of turbulent
Rayleigh-Benard convection. In these systems reversals occur
respectively for the dynamo magnetic field, for the large-scale
circulation generated by a periodic forcing in space and for the
large-scale roll generated by turbulent thermal convection. We compare
the mechanisms involved and show that their properties depend on some
symmetries of the system and on the way they are broken.