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(abridged) Context: Turbulent diffusion of large-scale flows and magnetic fields play major roles in many astrophysical systems. Aims: Our goal is to compute turbulent viscosity and magnetic diffusivity, relevant for diffusing large-scale…

Solar and Stellar Astrophysics · Physics 2020-04-29 Petri J. Käpylä , Matthias Rheinhardt , Axel Brandenburg , Maarit J. Käpylä

Buoyancy-induced (Rayleigh-Benard) convection of a fluid between two horizontal plates is a central paradigm for studying the transition to complex spatiotemporal dynamics in sustained nonequilibrium systems. To improve the analysis of…

Pattern Formation and Solitons · Physics 2007-05-23 M. C. Lai , K. H. Chiam , M. C. Cross , H. S. Greenside

The scaling law for the horizontal length scale $\ell$ relative to the domain height $L$, originating from the linear theory of quasi-static magnetoconvection, $\ell/L \sim Q^{-1/6}$, has been verified through two-dimensional (2D) direct…

Fluid Dynamics · Physics 2023-10-13 Shujaut H. Bader , Xiaojue Zhu

To study properties of magneto-hydrodynamic (MHD) convection and resultant dynamo activities in proto-neutron stars (PNSs), we construct a "PNS in a box" simulation model with solving compressible MHD equation coupled with a nuclear…

High Energy Astrophysical Phenomena · Physics 2022-02-21 Youhei Masada , Tomoya Takiwaki , Kei Kotake

We investigate the Lagrangian mechanism of the kinematic ``fluctuation'' magnetic dynamo in turbulent plasma flow at small magnetic Prandtl numbers. The combined effect of turbulent advection and plasma resistivity is to carry infinitely…

Plasma Physics · Physics 2015-05-13 Gregory L. Eyink , Antonio F. Neto

We report the existence of two new limiting turbulent regimes in horizontal convection (HC) using direct numerical simulations at intermediate to low Prandtl numbers. The flow driven by a horizontal gradient along a horizontal surface,…

Fluid Dynamics · Physics 2020-05-01 Pierre-Yves Passaggia , Alberto Scotti , Brian L. White

Regions of quiet Sun generally exhibit a complex distribution of small-scale magnetic field structures, which interact with the near-surface turbulent convective motions. Furthermore, it is probable that some of these magnetic fields are…

Solar and Stellar Astrophysics · Physics 2015-06-18 Paul J. Bushby , Benjamin Favier

Conceptual and theoretical models describing the dynamics of the atmosphere often assume a hierarchy of dynamic regimes, each operating over some limited range of spatial scales. The largest scales are presumed to be governed by…

Atmospheric and Oceanic Physics · Physics 2025-10-29 Thomas D. DeWitt , Timothy J. Garrett

The effect of a homogeneous magnetic field on surface-tension-driven B\'{e}nard convection is studied by means of direct numerical simulations. The flow is computed in a rectangular domain with periodic horizontal boundary conditions and…

Fluid Dynamics · Physics 2009-11-23 Thomas Boeck

We present a new mechanism for generation of large-scale magnetic field by thermal convection which does not involve the alpha-effect. We consider weakly nonlinear perturbations of space-periodic steady convective magnetic dynamos in a…

Fluid Dynamics · Physics 2015-12-01 Roman Chertovskih , Vladislav Zheligovsky

The present-day Universe is highly magnetized, even though the first magnetic seed fields were most probably extremely weak. To explain the growth of the magnetic field strength over many orders of magnitude fast amplification processes…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Jennifer Schober , Dominik Schleicher , Stefano Bovino , Ralf S. Klessen

Flow reversals are rarely observed in low-Prandtl-number liquid metal convection due to the fluid's exceptionally high thermal diffusivity. Here, we demonstrate that an external transverse magnetic field can induce such reversals in a…

Fluid Dynamics · Physics 2025-11-11 Yan-Wu Cao , Ming-Zhu Ai , Long Chen , Juan-Cheng Yang , Ming-Jiu Ni

A model for homogeneous anisotropic incompressible turbulence is proposed. The model generalizes the GISS model of homogeneous isotropic turbulence; the generalization involves the solution of the GISS equations along a set of integration…

Astrophysics · Physics 2015-06-24 Kristof Petrovay

This article is concerned with the kinetic modeling, by means of the Vlasov equation, of charged particles under the influence of a strong external electromagnetic field, i.e. when epsilon^2, the dimensionless cyclotron period, tends to…

Mathematical Physics · Physics 2009-05-15 Pierre Degond , Sever Hirstoaga , Marie-Hélène Vignal

In fluid dynamics, the scaling behaviour of flow length scales is commonly used to infer the governing force balance of a system. The key to a successful approach is to measure length scales that are representative of the energy contained…

Geophysics · Physics 2020-12-01 Tobias Schwaiger , Thomas Gastine , Julien Aubert

Using a nonlinear mean-field solar dynamo model, we study relationships between the amplitude of the `extended' mode of migrating zonal flows (`torsional oscillations') and magnetic cycles, and investigate whether properties the torsional…

Solar and Stellar Astrophysics · Physics 2020-09-02 V. V. Pipin , A. G. Kosovichev

We present a method to characterize the spectral transfers of magnetic energy between scales in simulations of stellar convective dynamos. The full triadic transfer functions are computed thanks to analytical coupling relations of spherical…

Solar and Stellar Astrophysics · Physics 2013-11-18 A. Strugarek , A. S. Brun , S. Mathis , Y. Sarazin

Recent analysis of the helioseismic observations indicate that the previously observed surface torsional oscillations extend significantly downwards into the solar convection zone. In an attempt to understand these oscillations, we study…

Astrophysics · Physics 2007-05-23 Eurico Covas , Reza Tavakol , David Moss , Andrew Tworkowski

This paper reports on a theoretical analysis of the rich variety of spatio-temporal patterns observed recently in inclined layer convection at medium Prandtl number when varying the inclination angle $\gamma$ and the Rayleigh number $R$.…

Using direct numerical simulations of the equations of magnetohydrodynamics, we study reversals of the magnetic field generated by the flow of an electrically conducting fluid in a sphere. We show that at low magnetic Prandtl numbers,…

Fluid Dynamics · Physics 2015-06-17 Pankaj Mishra , Christophe Gissinger , Emmanuel Dormy , Stephan Fauve