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We study the evolution of non-linear circularly polarised Alfven waves by solving numerically the time-dependent equations of magnetohydrodynamics (MHD) in one dimension. We examine the behaviour of the waves and find that different…

Astrophysics · Physics 2009-11-10 Rim Turkmani , Ulf Torkelsson

Mode conversion in the region where the sound and Alfven speeds are equal is a complex process, which has been studied both analytically and numerically, and has been seen in observations. In order to further the understanding of this…

Astrophysics · Physics 2008-08-04 A. M. Dee McDougall , Alan W. Hood

Molecular clouds have broad linewidths suggesting turbulent supersonic motions in the clouds. These motions are usually invoked to explain why molecular clouds take much longer than a free-fall time to form stars. It has classically been…

Astrophysics · Physics 2011-02-11 Mordecai-Mark Mac Low

The present study is concerned with the stability of a flow of viscous conducting liquid driven by pressure gradient in the channel between two parallel walls subject to a transverse magnetic field. Although the magnetic field has a strong…

Fluid Dynamics · Physics 2014-12-04 Jonathan Hagan , Jānis Priede

We explore the structure and statistics of multiphase, magnetized ISM turbulence in the local Milky Way by means of driven periodic box numerical MHD simulations. Using the higher order-accurate piecewise-parabolic method on a local stencil…

Astrophysics of Galaxies · Physics 2017-06-19 Alexei G. Kritsuk , Sergey D. Ustyugov , Michael L. Norman

The role of short-wave instabilities on geostrophic turbulence is studied in a simplified model consisting of three layers in the quasi-geostrophic approximation. The linear stability analysis shows that short-wave instabilities are created…

Fluid Dynamics · Physics 2015-10-21 Gualtiero Badin

Recent observational evidence that magnetic fields are dynamically important in molecular clouds, compared to self-gravity and turbulence, is reviewed and illustrated with data from the NGC 2024 region. One piece of evidence, turbulence…

Astrophysics of Galaxies · Physics 2015-05-19 Hua-bai Li , Raymond Blundell , Abigail Hedden , Jonathan Kawamura , Scott Paine , Edward Tong

We briefly review helicity dynamics, inverse and bi-directional cascades in fluid and magnetohydrodynamic (MHD) turbulence, with an emphasis on the latter. The energy of a turbulent system, an invariant in the non-dissipative case, is…

Fluid Dynamics · Physics 2019-03-13 A. Pouquet , D. Rosenberg , J. E. Stawarz , R. Marino

Boundary layer processes drive the air-sea exchange of momentum, heat, and moisture that powers and shapes hurricanes. The height of the boundary layer is a critical parameter in engineering and meteorological models of hurricane wind…

Fluid Dynamics · Physics 2026-05-06 Kishore Ram Sathia , Marco Giovanni Giometto

Using the magnetohydrodynamic (MHD) description, we develop a nonlinear dynamo model that couples the evolution of the large scale magnetic field with turbulent dynamics of the plasma at small scale by electromotive force (e.m.f.) in the…

Earth and Planetary Astrophysics · Physics 2011-09-29 Giuseppina Nigro , Pierlugi Veltri

We present the results of simulations of forced turbulence in a slab where the mean kinetic helicity has a maximum near the mid-plane, generating gradients of magnetic helicity of both large and small-scale fields. We also study systems…

Solar and Stellar Astrophysics · Physics 2010-11-30 A. Hubbard , A. Brandenburg

Recent advances in understanding of magnetohydrodynamic (MHD) turbulence call for revisions in the picture of particle acceleration. We make use of the recently established scaling of slow and fast MHD modes in strong and weak MHD…

Astrophysics · Physics 2016-08-30 Jungyeon Cho , A. Lazarian

Compressible turbulence, especially the magnetized version of it, traditionally has a bad reputation with researchers. However, recent progress in theoretical understanding of incompressible MHD as well as that in computational capabilities…

Astrophysics · Physics 2007-05-23 Jungyeon Cho , A. Lazarian

Powerful stellar winds and supernova explosions with intense energy release in the form of strong shock waves can convert a sizeable part of the kinetic energy release into energetic particles. The starforming regions are argued as a…

High Energy Astrophysical Phenomena · Physics 2015-06-12 A. M. Bykov , P. E. Gladilin , S. M. Osipov

Vertically stable in density, stratified-water conditions 'SW' exist in the deep Mediterranean Sea that are characterized by temperature differences of 0.0002-0.01degrC over 125 m above a flat seafloor. These result in a mean buoyancy…

Atmospheric and Oceanic Physics · Physics 2026-01-09 Hans van Haren

The limitations of Hall MHD as a model for turbulence in weakly collisional plasmas are explored using quantitative comparisons to Vlasov-Maxwell kinetic theory over a wide range of parameter space. The validity of Hall MHD in the cold ion…

Solar and Stellar Astrophysics · Physics 2020-01-29 Gregory G. Howes

We investigate experimentally phenomenon of turbulent thermal diffusion of micron-size solid particles in an inhomogeneous convective turbulence forced by one vertically-oriented oscillating grid in an air flow. This effect causes formation…

Fluid Dynamics · Physics 2024-04-19 E. Elmakies , O. Shildkrot , N. Kleeorin , A. Levy , I. Rogachevskii

We conduct a three-dimensional magnetohydrodynamic (MHD) simulation of the parametric decay instability of Alfv\'en waves and resultant compressible MHD turbulence, which is likely to develop in the solar wind acceleration region. Because…

Solar and Stellar Astrophysics · Physics 2018-06-06 Munehito Shoda , Takaaki Yokoyama

While the rising flux tube paradigm is an elegant theory, its basic assumptions, thin flux tubes at the bottom of the convection zone with field strengths two orders of magnitude above equipartition, remain numerically unverified at best.…

Solar and Stellar Astrophysics · Physics 2012-08-17 K. Kemel , A. Brandenburg , N. Kleeorin , I. Rogachevskii

Density stratification in geophysical environments can be non-uniform, particularly in thermohaline staircases and atmospheric layer transitions. Non-uniform stratification, however, is often approximated by the average ambient density…

Fluid Dynamics · Physics 2020-11-10 G. D. Portwood , S. M. de Bruyn Kops