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Intermittency in fluid turbulence can be emphasized through the analysis of Probability Distribution Functions (PDF) for velocity fluctuations, which display a strong non-gaussian behavior at small scales. Castaing et al. (1990) have…

Intermittency in MHD turbulence has been analyzed using high resolution 2D numerical simulations. We show that the Probability Distribution Functions (PDFs) of the fluctuations of the Elsasser fields, magnetic field and velocity field…

Chaotic Dynamics · Physics 2015-06-26 L. Sorriso-Valvo , V. Carbone , P. Veltri , H. Politano , A. Pouquet

The probability density functions (PDFs) for energy dissipation rates, created from time-series data of grid turbulence in a wind tunnel, are analyzed in a high precision by the theoretical formulae for PDFs within multifractal PDF theory…

Fluid Dynamics · Physics 2015-06-03 Toshihico Arimitsu , Naoko Arimitsu , Hideaki Mouri

Intermittency in fluid turbulence can be evidentiated through the analysis of Probability Distribution Functions (PDF) of velocity fluctuations, which display a strong non-gaussian behavior at small scales. In this paper we investigate the…

Chaotic Dynamics · Physics 2007-05-23 V. Carbone , P. Giuliani , L. Sorriso-Valvo , P. Veltri , R. Bruno , E. Martines , V. Antoni

We study energy dissipation and heating by supersonic MHD turbulence in molecular clouds using Athena, a new higher-order Godunov code. We analyze the dependence of the saturation amplitude, energy dissipation characteristics, power…

Astrophysics · Physics 2011-02-11 M. Nicole Lemaster , James M. Stone

Simulations generally show that non-self-gravitating clouds have a lognormal column density ($\Sigma$) probability distribution function (PDF), while self-gravitating clouds with active star formation develop a distinct power-law tail at…

Astrophysics of Galaxies · Physics 2017-12-20 Sayantan Auddy , Shantanu Basu , Takahiro Kudoh

In this Letter we investigate the shape of the probability distribution of column densities (PDF) in molecular clouds. Through the use of low-noise, extinction-calibrated \textit{Herschel}/\textit{Planck} emission data for eight molecular…

Solar and Stellar Astrophysics · Physics 2015-06-23 Marco Lombardi , João Alves , Charles J. Lada

Supersonic turbulence occurs in many environments, particularly in astrophysics. In the crucial case of isothermal turbulence, the probability density function (PDF) of the logarithmic density, $s$, is well measured, but a theoretical…

Astrophysics of Galaxies · Physics 2024-10-31 Evan Scannapieco , Liubin Pan , Edward Buie , Marcus Brüggen

By means of the multifractal analysis (MFA), the expressions of the probability density functions (PDFs) are unified in a compact analytical formula which is valid for various quantities in turbulence. It is shown that the formula can…

Statistical Mechanics · Physics 2009-11-10 Toshihico Arimitsu , Naoko Arimitsu

Turbulence is a complex phenomenon that plays a critical role in the interstellar medium (ISM). Previous simulations and observations show that the probability density function (PDF) of gas density in isothermal and compressible systems…

Astrophysics of Galaxies · Physics 2025-03-26 Xunchuan Liu

We study the effect of density fluctuations induced by turbulence on the HI/H$_2$ structure in photodissociation regions (PDRs) both analytically and numerically. We perform magnetohydrodynamic numerical simulations for both subsonic and…

Astrophysics of Galaxies · Physics 2017-07-26 Shmuel Bialy , Blakesley Burkhart , Amiel Sternberg

We introduce a method for calculating the probability density function (PDF) of a turbulent density field in three dimensions using only information contained in the projected two-dimensional column density field. We test the method by…

Astrophysics of Galaxies · Physics 2015-05-18 Christopher M. Brunt , Christoph Federrath , Daniel J. Price

The probability density function (PDF) of the gas density in turbulent supersonic flows is investigated with high-resolution numerical simulations. In a systematic study, we compare the density statistics of compressible turbulence driven…

Astrophysics · Physics 2009-11-13 Christoph Federrath , Ralf S. Klessen , Wolfram Schmidt

It is widely accepted that supersonic, magnetised turbulence plays a fundamental role for star formation in molecular clouds. It produces the initial dense gas seeds out of which new stars can form. However, the exact relation between gas…

Astrophysics of Galaxies · Physics 2012-04-13 F. Z. Molina , S. C. O. Glover , C. Federrath , R. S. Klessen

Both observational and theoretical research over the past decade has demonstrated that the probability distribution function (PDF) of the gas density in turbulent molecular clouds is a key ingredient for understanding star formation. It has…

Astrophysics of Galaxies · Physics 2018-11-28 Bastian Körtgen , Christoph Federrath , Robi Banerjee

The probability density function (PDF) of velocity fluctuations is studied experimentally for grid turbulence in a systematical manner. At small distances from the grid, where the turbulence is still developing, the PDF is sub-Gaussian. At…

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

The structure of molecular clouds can be characterized with the probability distribution function (PDF) of the mass surface density. In particular, the properties of the distribution can reveal the nature of the turbulence and star…

Astrophysics of Galaxies · Physics 2015-06-22 Rachel L. Ward , James Wadsley , Alison Sills

The statistical properties of the $E \times B$ flux in different types of plasma turbulence simulations are investigated using probability density distribution functions (PDF). The physics included in the models ranges from two dimensional…

Plasma Physics · Physics 2009-11-10 Volker Naulin , Odd Erik Garcia , Anders Henry Nielsen , Jens Juul Rasmussen

We discuss the generation and statistics of the density fluctuations in highly compressible polytropic turbulence, based on a simple model and one-dimensional numerical simulations. Observing that density structures tend to form in a…

Fluid Dynamics · Physics 2009-10-31 Thierry Passot , Enrique Vazquez-Semadeni

We investigate the form of the one-point probability distribution function (pdf) for the density field of the interstellar medium using numerical simulations that successively reduce the number of physical processes included.…

Astrophysics · Physics 2014-10-13 J. Scalo , E. Vazquez-Semadeni , D. Chappell , T. Passot