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The generation of large scale flows by the anisotropic kinetic alpha (AKA) effect is investigated in simulations with a suitable time-dependent space- and time-periodic anisotropic forcing lacking parity invariance. The forcing pattern…

Astrophysics · Physics 2007-05-23 A. Brandenburg , B. v. Rekowski

Three-dimensional turbulence is usually studied experimentally by using a spatially localized forcing at large scales (e.g. via rotating blades or oscillating grids), often in a deterministic way. Here, we report an original technique where…

In novel ultra-pure materials electrons can form a viscous fluid, which is fundamentally different by its dynamics from the electron gas in ordinary conductors with significant density of defects. The shape of the non-stationary flow of…

Mesoscale and Nanoscale Physics · Physics 2022-07-28 A. N. Afanasiev , P. S. Alekseev , A. A. Danilenko , A. A. Greshnov , M. A. Semina

Combined action of helical motions of plasma (the $\alpha$ effect) and non-uniform (differential) rotation is a key dynamo mechanism of solar and galactic large-scale magnetic fields. Dynamics of magnetic helicity of small-scale fields is a…

Solar and Stellar Astrophysics · Physics 2022-09-20 N. Kleeorin , I. Rogachevskii

We present numerical simulations of three-dimensional compressible magnetoconvection in a rotating rectangular box that represents a section of the solar convection zone. The box contains a convectively unstable layer, surrounded by stably…

Astrophysics · Physics 2009-11-07 M. Ossendrijver , M. Stix , A. Brandenburg

Using simulations of slowly rotating stratified turbulence, we show that the alpha effect responsible for the generation of astrophysical magnetic fields is proportional to the logarithmic gradient of kinetic energy density rather than that…

Solar and Stellar Astrophysics · Physics 2012-12-27 A. Brandenburg , O. Gressel , P. J. Käpylä , N. Kleeorin , M. J. Mantere , I. Rogachevskii

Fermions become polarized in a vortical fluid due to spin-vorticity coupling. The spin polarization density is proportional to the local fluid vorticity at the next-to-leading order of a gradient expansion in a quantum kinetic theory. Spin…

High Energy Physics - Phenomenology · Physics 2016-11-09 Long-Gang Pang , Hannah Petersen , Qun Wang , Xin-Nian Wang

The influence of turbulent effects on a fluid flow through a (pseudo) porous media is studied by numerically solving the set of Reynolds-averaged Navier-Stokes equations with the $\kappa$-$\epsilon$ model for turbulence. The spatial domains…

Statistical Mechanics · Physics 2009-11-07 H. H. M. Vasconcelos , U. M. S. Costa , M. P. Almeida

We analyze direct numerical simulations of large-scale dynamos in inhomogeneous nonhelically driven rotating turbulence with and without shear. The forcing is modulated so that the turbulent intensity peaks in the middle of the…

Plasma Physics · Physics 2025-05-02 Axel Brandenburg , Ethan T. Vishniac

In-situ observations in the Earth's and Saturn's magnetosheaths and in the solar wind reveal the presence of Alfv\'en vortices as intermittent structures in the range of scales from fluid lengths down to few ion lengths. The density and the…

Plasma Physics · Physics 2020-04-16 Dusan Jovanovic , Olga Alexandrova , Milan Maksimovic , Milivoj Belic

A theoretical and experimental study of the spin-over mode induced by the elliptical instability of a flow contained in a slightly deformed rotating spherical shell is presented. This geometrical configuration mimics the liquid rotating…

Classical Physics · Physics 2016-08-16 L. Lacaze , P. Le Gal , S. Le Dizès

In an electrically conducting fluid, vortices stretch out a weak, large-scale magnetic field to form strong current sheets on their edges. Associated with these current sheets are magnetic stresses, which are subsequently released through…

Fluid Dynamics · Physics 2016-09-13 Julian Mak , Stephen D. Griffiths , D. W. Hughes

We investigate the impact of a solid-body rotation $\Omega_0$ on the large-scale dynamics of an incompressible magnetohydrodynamic turbulent flow in presence of a background magnetic field $\bf B_0$ and at low Rossby number.…

Fluid Dynamics · Physics 2019-07-24 Mélissa D. Menu , Sébastien Galtier , Ludovic Petitdemange

The axisymmetric 3-D MHD outflow of a cold plasma from a magnetized and rotating astrophysical object is numerically simulated with the purpose of investigating the outflow's magnetocentrifugal acceleration and eventual collimation. Gravity…

Astrophysics · Physics 2009-10-31 S. Bogovalov , K. Tsinganos

We analytically examine fluctuations of vorticity excited by an external random force in two-dimensional fluid. We develop the perturbation theory enabling one to calculate nonlinear corrections to correlation functions of the flow…

Fluid Dynamics · Physics 2024-03-28 I. V. Kolokolov , V. V. Lebedev , V. M. Parfenyev

Understanding the dynamics of material objects advected by turbulent flows is a long standing question in fluid dynamics. In this perspective article we focus on the characterization of the statistical properties of non-interacting…

Fluid Dynamics · Physics 2024-03-18 Yaning Fan , Cheng Wang , Linfeng Jiang , Chao Sun , Enrico Calzavarini

We analyse the tumbling of small non-spherical, axisymmetric particles in random and turbulent flows. We compute the orientational dynamics in terms of a perturbation expansion in the Kubo number, and obtain the tumbling rate in terms of…

Fluid Dynamics · Physics 2015-06-15 K. Gustavsson , J. Einarsson , B. Mehlig

We study a new type of large-scale instability, which arises in obliquely rotating stratified electroconductive fluid with an external uniform magnetic field and a small-scale external force having zero helicity. This force gives rise to…

Fluid Dynamics · Physics 2018-07-06 M. I. Kopp , K. N. Kulik , A. V. Tur , V. V. Yanovsky

We present a study of spectral laws for helical turbulence in the presence of solid body rotation up to Reynolds numbers Re~1*10^5 and down to Rossby numbers Ro~3*10^-3. The forcing function is a fully helical flow that can also be viewed…

Fluid Dynamics · Physics 2009-12-18 J. Baerenzung , D. Rosenberg , P. D. Mininni , A. Pouquet

We study the effect of turbulent drift of a large-scale magnetic field that results from the interaction of helical convective motions and differential rotation in the solar convection zone. The principal direction of the drift corresponds…

Solar and Stellar Astrophysics · Physics 2015-06-05 V. V. Pipin
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