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Turbulent dynamics generate random fluctuations in density and velocity in the Interstellar Medium (ISM) of spiral and dwarf galaxies. Observationally, H~{\sc i} 21-cm radiation provides a good probe of these stochastic processes and helps…

Astrophysics of Galaxies · Physics 2018-05-30 Meera Nandakumar

X-ray observations of galaxy clusters provide insights on the nature of gaseous turbulent motions, their physical scales and on the fundamental processes they are related to. Spatially-resolved, high-resolution spectral measurements of…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-25 N. Clerc , E. Cucchetti , E. Pointecouteau , P. Peille

Supersonic turbulence fragments the interstellar medium into dense sheets, filaments, cores and large low density voids. The turbulence is driven on large scales, probably predominantly by supernovae. The scaling properties of supersonic…

Astrophysics · Physics 2007-05-23 Aake Nordlund , Paolo Padoan

We assemble a homogeneous database of precise and consistent determinations of effective temperature, surface gravity, projected rotational rate, and macro- and micro-turbulent velocities for over 1800 Galactic stars spanning spectral types…

Solar and Stellar Astrophysics · Physics 2025-10-01 N. Markova , M. Cantiello , L. Grassitelli

In star-forming clouds, high velocity flow gives rise to large fluctuations of density. In this work we explore the correlation between velocity magnitude (speed) and density. We develop an analytic formula for the joint probability…

Astrophysics of Galaxies · Physics 2023-08-02 Branislav Rabatin , David C. Collins

Turbulent motions induce Doppler shifts of observable emission and absorption lines motivating studies of turbulence using precision spectroscopy. We provide the numerical testing of the two most promising techniques, Velocity Channel…

Astrophysics · Physics 2009-09-29 A. Chrupnov , A. Lazarian

We use well-resolved direct numerical simulations of high-Reynolds-number turbulence to study a fundamental statistical property of turbulence -- the asymmetry of velocity increments -- with likely implications on important dynamics. This…

Fluid Dynamics · Physics 2022-10-11 Katepalli R. Sreenivasan , Kartik P. Iyer , Ashvin Vinodh

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

Sub-mm observations of protoplanetary disks now approach the acuity needed to measure the turbulent broadening of molecular lines. These measurements constrain disk angular momentum transport, and furnish evidence of the turbulent…

Solar and Stellar Astrophysics · Physics 2015-05-28 Jacob B. Simon , Philip J. Armitage , Kris Beckwith

A two-field Hamiltonian gyrofluid model for kinetic Alfv\'en waves retaining ion finite Larmor radius corrections, parallel magnetic field fluctuations and electron inertia, is used to study turbulent cascades from the MHD to the sub-ion…

Plasma Physics · Physics 2019-05-29 T. Passot , P. L. Sulem

Superfluid Turbulence is unusual and presents a challenge to fluid dynamicists because it consists of two coupled, inter penetrating turbulent fluids: the first is inviscid with quantised vorticity, the second is viscous with continuous…

Other Condensed Matter · Physics 2013-06-27 Carlo F. Barenghi , Victor L'vov , Philippe-E. Roche

We propose and validate a novel experimental technique to measure two-point statistics of turbulent flows. It consists in spreading rigid fibers in the flow and tracking their position and orientation in time and therefore been named…

We report results from a high resolution numerical study of fluid particles transported by a fully developed turbulent flow. Single particle trajectories were followed for a time range spanning more than three decades, from less than a…

Chaotic Dynamics · Physics 2009-11-11 Luca Biferale , Federico Toschi

The streamwise and transverse velocities are measured simultaneously in isotropic grid turbulence at relatively high Reynolds numbers, Re(lambda) = 110-330. Using a conditional averaging technique, we extract typical intermittency patterns,…

Fluid Dynamics · Physics 2009-11-07 H. Mouri , A. Hori , Y. Kawashima

Time scales of turbulent strain activity, denoted as the strain persistence times of first and second order, are obtained from time-dependent expectation values and correlation functions of lagrangian rate-of-strain eigenvalues taken in…

Fluid Dynamics · Physics 2014-01-06 L. Moriconi , R. M. Pereira

We used magnetohydrodynamic (MHD) simulations of interstellar turbulence to study the probability distribution functions (PDFs) of increments of density, velocity, and magnetic field. We found that the PDFs are well described by a Tsallis…

Astrophysics of Galaxies · Physics 2011-08-04 A. Esquivel , A. Lazarian

We performed high resolution numerical simulations of homogenous and isotropic compressible turbulence, with an average 3D Mach number close to 0.3. We study the statistical properties of intermittency for velocity, density and entropy. For…

Chaotic Dynamics · Physics 2009-11-13 Roberto Benzi , Luca Biferale , Robert Fisher , Leo Kadanoff , Donald Lamb , Federico Toschi

The transitional regime of plane channel flow is investigated {above} the transitional point below which turbulence is not sustained, using direct numerical simulation in large domains. Statistics of laminar-turbulent spatio-temporal…

Fluid Dynamics · Physics 2020-09-16 Pavan V. Kashyap , Yohann Duguet , Olivier Dauchot

The velocity fluctuations for point vortex models are studied for the {\alpha}-turbulence equations, which are characterized by a fractional Laplacian relation between active scalar and the streamfunction. In particular, we focus on the…

Fluid Dynamics · Physics 2019-09-11 Giovanni Conti , Gualtiero Badin

We study inertial-range statistics in the direct enstrophy cascade of two-dimensional turbulence via a numerical simulation of the forced Navier-Stokes equation. In particular, we obtain the distribution of the enstrophy flux and of the…

Chaotic Dynamics · Physics 2007-05-23 Xin Wang , Shiyi Chen , Robert E. Ecke , Gregory L. Eyink