177 citations · 2.4k across the 68 of their papers we have counts for
10 papers · 1 filter
Mean-field closure parameters for passive scalar turbulence
J. E. Snellman, M. Rheinhardt, P. J. Käpylä +2
Direct numerical simulations of isotropically forced homogeneous stationary turbulence with an imposed passive scalar concentration gradient are compared with an analytical closure…
Ejections of magnetic structures above a spherical wedge driven by a convective dynamo with differential rotation
Jörn Warnecke, Petri J. Käpylä, Maarit. J. Mantere +1
We combine a convectively driven dynamo in a spherical shell with a nearly isothermal density-stratified cooling layer that mimics some aspects of a stellar corona to study the eme…
Oscillatory large-scale dynamos from Cartesian convection simulations
P. J. Käpylä, M. J. Mantere, A. Brandenburg
We present results from compressible Cartesian convection simulations with and without imposed shear. In the former case the dynamo is expected to be of type which i…
Verification of Reynolds stress parameterizations from simulations
J. E. Snellman, A. Brandenburg, P. J. Käpylä +1
We determine the timescales associated with turbulent diffusion and isotropization in closure models using anisotropically forced and freely decaying turbulence simulations and to…
Effects of stratification in spherical shell convection
P. J. Käpylä, M. J. Mantere, A. Brandenburg
We report on simulations of mildly turbulent convection in spherical wedge geometry with varying density stratification. We vary the density contrast within the convection zone by…
Starspots due to large-scale vortices in rotating turbulent convection
P. J. Käpylä, M. J. Mantere, T. Hackman
We study the generation of large-scale vortices in rotating turbulent convection by means of Cartesian direct numerical simulations. We find that for sufficiently rapid rotation, c…
Pumping velocity in homogeneous helical turbulence with shear
I. Rogachevskii, N. Kleeorin, P. Käpylä +1
Using different analytical methods (the quasi-linear approach, the path-integral technique and tau-relaxation approximation) we develop a comprehensive mean-field theory for a pump…
Negative effective magnetic pressure in turbulent convection
P. J. Käpylä, A. Brandenburg, N. Kleeorin +2
We investigate the effects of weakly and strongly stratified turbulent convection on the mean effective Lorentz force, and especially on the mean effective magnetic pressure. Earli…
From convective to stellar dynamos
A. Brandenburg, P. J. Käpylä, M. J. Korpi
Convectively driven dynamos with rotation generating magnetic fields on scales large compared with the scale of the turbulent eddies are being reviewed. It is argued that such fiel…
Dynamo action and magnetic buoyancy in convection simulations with vertical shear
G. Guerrero, P. Käpylä
A hypothesis for sunspot formation is the buoyant emergence of magnetic flux tubes created by the strong radial shear at the tachocline. In this scenario, the magnetic field has to…