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The statistical properties of turbulence are considered to be universal at sufficiently small length scales, i. e., independent of boundary conditions and large-scale forces acting on the fluid. Analyzing data from numerical simulations of…

Astrophysics · Physics 2008-12-18 Wolfram Schmidt , Christoph Federrath , Ralf Klessen

Kinematic dynamo theory is presented here for turbulent conductive fluids. We describe how inhomogeneous magnetic fluctuations are generated below the viscous scale of turbulence where the spatial smoothness of the velocity permits a…

chao-dyn · Physics 2009-10-31 M. Chertkov , G. Falkovich , I. Kolokolov , M. Vergassola

Our attention focuses on the stochastic dynamo equation with non-normal operator that give an insight into the role of stochastics and non-normality in the galactic magnetic field generation. The main point of this Letter is a discussion of…

Astrophysics · Physics 2009-11-07 Sergei Fedotov

Several recent studies have demonstrated how large-scale vortices may arise spontaneously in rotating planar convection. Here we examine the dynamo properties of such flows in rotating Boussinesq convection. For moderate values of the…

Fluid Dynamics · Physics 2017-03-01 Céline Guervilly , David W. Hughes , Chris A. Jones

Small-scale turbulent dynamo is responsible for the amplification of magnetic fields on scales smaller than the driving scale of turbulence in diverse astrophysical media. Most earlier dynamo theories concern the kinematic regime and…

Astrophysics of Galaxies · Physics 2021-06-25 Siyao Xu , Alex Lazarian

A quasi-linear theory is presented for how randomly forced, barotropic velocity fluctuations cause an exponentially-growing, large-scale (mean) magnetic dynamo in the presence of a uniform shear flow, $\vec{U} = S x \vec{e}_y$. It is a…

Astrophysics of Galaxies · Physics 2015-05-30 James C. McWilliams

The features of turbulence modulation produced by a heavy loaded suspension of small solid particles or liquid droplets are discussed by using a physically-based regularisation of particle-fluid interactions. The approach allows a robust…

Fluid Dynamics · Physics 2017-04-05 P. Gualtieri , F. Battista , C. M. Casciola

We explore the decay of turbulence and magnetic fields generated by fluctuation dynamo action in the context of galaxy clusters where such a decaying phase can occur in the aftermath of a major merger event. Using idealized numerical…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-28 Sharanya Sur

The $\Lambda$ effect describes a rotation-induced non-diffusive contribution to the Reynolds stress. It is commonly held responsible for maintaining the observed differential rotation of the Sun and other late-type stars. Here the…

Solar and Stellar Astrophysics · Physics 2020-02-18 Petri J. Käpylä

An initially planar shock wave propagating into a medium of non-uniform density will be perturbed, leading to the generation of post-shock velocity perturbations. Using numerical simulations we study this phenomenon in the case of…

Scaling in the dynamical properties of complex many-body systems has been of strong interest since turbulence phenomena became the subject of systematic mathematical studies. In this article, dynamical critical phenomena far from…

Quantum Gases · Physics 2015-08-27 Steven Mathey , Thomas Gasenzer , Jan M. Pawlowski

We study the properties of sub-Alfvenic magnetohydrodynamic (MHD) turbulence, i.e., turbulence with Alfven Mach number $M_A=V_L/V_A<1$, where $V_L$ is the velocity at the injection scale and $V_A$ is the Alfven velocity. We demonstrate that…

Astrophysics of Galaxies · Physics 2024-10-28 Alex Lazarian , Ka Wai HO , Ka Ho Yuen , Ethan Vishniac

We use three-dimensional direct numerical simulations of the helically forced magnetohydrodynamic equations in spherical shell segments in order to study the effects of changes in the geometrical shape and size of the domain on the growth…

Astrophysics · Physics 2010-01-15 Dhrubaditya Mitra , Reza Tavakol , Axel Brandenburg , David Moss

Turbulence is a fundamental flow phenomenon, typically anisotropic at large scales and approximately isotropic at small scales. The classical Kolmogorov scaling laws (2/3, -5/3 and 4/5) have been well-established for turbulence without…

Fluid Dynamics · Physics 2025-04-08 Yong-Ying Zeng , Zi-Ju Liao , Jun-Yi Li , Wei-Dong Su

Coagulation driven by supersonic turbulence is primarily an astrophysical problem because coagulation processes on Earth are normally associated with incompressible fluid flows at low Mach numbers, while dust aggregation in the interstellar…

Fluid Dynamics · Physics 2021-04-30 Xiang-Yu Li , Lars Mattsson

An update is given on the current status of solar and stellar dynamos. At present, it is still unclear why stellar cycle frequencies increase with rotation frequency in such a way that their ratio increases with stellar activity. The…

Solar and Stellar Astrophysics · Physics 2015-06-15 Axel Brandenburg

Nonhelical hydromagnetic forced turbulence is investigated using large scale simulations on up to 256 processors and $1024^3$ meshpoints. The magnetic Prandtl number is varied between 1/8 and 30, although in most cases it is unity. When the…

Astrophysics · Physics 2007-05-23 Nils Erland L. Haugen , Axel Brandenburg , Wolfgang Dobler

Fast magnetosonic waves are among the fundamental oscillation modes of astrophysical plasmas. To study their dynamics, we carry out numerical simulations of the wave turbulence kinetic equation, which describes the evolution of the energy…

Plasma Physics · Physics 2026-05-22 Nicolás Pablo Müller , Sébastien Galtier

We use high resolution direct numerical simulations (DNS) to show that helical turbulence can generate significant large-scale fields even in the presence of strong small-scale dynamo action. During the kinematic stage, the unified…

Astrophysics of Galaxies · Physics 2016-07-01 Pallavi Bhat , Kandaswamy Subramanian , Axel Brandenburg

We use large-scale three-dimensional simulations of supersonic Euler turbulence to study the physics of a highly compressible cascade. Our numerical experiments describe non-magnetized driven turbulent flows with an isothermal equation of…

Astrophysics · Physics 2009-06-23 Alexei G. Kritsuk , Paolo Padoan , Rick Wagner , Michael L. Norman