Dynamo action at low magnetic Prandtl numbers: mean flow vs. fully turbulent motion

Creators: Ponty, Yannick; Mininni, Pablo; Pinton, Jean-François; Politano, Hélène; Pouquet, Annick

Others:: Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE) ; Université Nice Sophia Antipolis (1965 - 2019) (UNS) ; COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur ; COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS); National Center for Atmospheric Research [Boulder] (NCAR); Laboratoire de Physique de l'ENS Lyon (Phys-ENS) ; École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL) ; Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)

Description

We compute numerically the threshold for dynamo action in Taylor-Green swirling flows. Kinematic calculations, for which the flow field is fixed to its time averaged profile, are compared to dynamical runs for which both the Navier-Stokes and the induction equations are jointly solved. The kinematic instability is found to have two branches, for all explored Reynolds numbers. The dynamical dynamo threshold follows these branches: at low Reynolds number it lies within the low branch while at high kinetic Reynolds number it is close to the high branch.

Abstract

4 pages, 4 figures

Dynamo action at low magnetic Prandtl numbers: mean flow vs. fully turbulent motion

Description

Abstract

Additional details