Speaker
Rakesh Yadav
(Max-Planck-Institut für Sonnensystemforschung, Lindau)
Description
Numerical dynamo models always operate at parameters which
are many orders of
magnitude smaller or larger than the values expected in natural
objects. However,
numerical modelling has been very successful in reproducing
many interesting
properties of dynamos existing in nature. This qualitative
agreement fuels the idea
that both numerical and natural systems are in an asymptotic
regime of dynamics where
the diffusive processes do not play an important role. Such
asymptotic regimes can be
probed using scaling studies.
In the recent past, scaling laws derived from relatively simple
dynamo simulations
have proven to be very fruitful: numerical models successfully
predict the mean
magnetic field strength of a broad range of astrophysical objects
encompassing Earth,
Jupiter, and some rapidly-rotating fully-convective stars. We
study more than 250 new
direct numerical simulations of Boussinesq and anelastic dynamos
in spherical shell
to extend earlier scaling laws derived from only Boussinesq
models. We find that the
scaling laws for heat transfer, mean kinetic and magnetic energy
in these systems are
very robust. Our study provides strong support for the
hypothesis that both mean
kinetic and magnetic energy relate to the power generated by
buoyancy forces via a
simple power law.
Primary authors
Lúcia D. V. Duarte
(Max-Planck-Institut für Sonnensystemforschung, Lindau)
Rakesh Yadav
(Max-Planck-Institut für Sonnensystemforschung, Lindau)
Thomas Gastine
(Max-Planck-Institut für Sonnensystemforschung, Lindau)
Ulrich R. Christensen
(Max-Planck-Institut für Sonnensystemforschung, Lindau)
