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We experimentally study density fluctuations and energy spectra of bulk \textit{E. coli} suspensions of different concentrations. Our results verify the predicted scaling law of giant number fluctuations in three-dimensional (3D) wet active…

Soft Condensed Matter · Physics 2021-10-28 Zhengyang Liu , Wei Zeng , Xiaolei Ma , Xiang Cheng

We provide a generic but physically clear discussion of the clustering properties of dark energy models. We explicitly show that in quintessence-type models the dark energy fluctuations, on scales smaller than the Hubble radius, are of the…

Astrophysics · Physics 2008-11-26 P. P. Avelino , L. M. G. Beca , C. J. A. P. Martins

For a freely evolving granular fluid, the buildup of spatial correlations in density and flow field is described using fluctuating hydrodynamics. The theory for incompressible flows is extended to the general, compressible case, including…

Statistical Mechanics · Physics 2009-10-30 T. P. C. van Noije , M. H. Ernst , R. Brito

The relationship between magnetic reconnection and plasma turbulence is investigated using multipoint in-situ measurements from the Cluster spacecraft within a high-speed reconnection jet in the terrestrial magnetotail. We show explicitly…

Space Physics · Physics 2015-12-23 K. T. Osman , K. H. Kiyani , W. H. Matthaeus , B. Hnat , S. C. Chapman , Yu. V. Khotyaintsev

In a follow-up study to a previous analysis of the IRAS 1.2Jy catalogue, we quantify the morphological fluctuations in the PSCz survey. We use a variety of measures, among them the family of scalar Minkowski functionals. We confirm the…

Astrophysics · Physics 2009-08-07 M. Kerscher , K. Mecke , J. Schmalzing , C. Beisbart , T. Buchert , H. Wagner

Turbulence develops in any stressed flow when the scales of the forcing are much larger than those of the dissipation. In neutral fluids, it consists of chaotic motions in physical space but with a universal energy spectrum in Fourier…

Turbulence is ubiquitous in plasmas, leading to rich dynamics characterized by irregularity, irreversibility, energy fluctuations across many scales, and energy transfer across many scales. Another fundamental and generic feature of…

Plasma Physics · Physics 2017-02-14 Vladimir Zhdankin , Stanislav Boldyrev , Dmitri A. Uzdensky

We examine the idea that diffuse and giant molecular clouds and their substructure form as density fluctuations induced by large scale interstellar turbulence. We do this by investigating the topology of various fields in realistic…

Astrophysics · Physics 2009-10-30 Javier Ballesteros-Paredes , Enrique Vazquez-Semadeni , John Scalo

We motivate the importance of studying kinetic scale turbulence for understanding the macroscopic properties of the heliosphere, such as the heating of the solar wind. We then discuss the technique by which kinetic scale density…

Space Physics · Physics 2013-06-25 C. H. K. Chen , G. G. Howes , J. W. Bonnell , F. S. Mozer , K. G. Klein , S. D. Bale

We study two limiting cases of turbulence forcing in numerical experiments: solenoidal (divergence-free) forcing, and compressive (curl-free) forcing, and compare our results to observations reported in the literature. We solve the…

Solar and Stellar Astrophysics · Physics 2010-07-16 C. Federrath , J. Roman-Duval , R. Klessen , W. Schmidt , M. -M. Mac Low

Interacting fluids, endowed with bulk viscous stresses, are discussed in a unified perspective with the aim of generalizing the treatment of cosmological perturbation theory to the case where both fluctuating decay rates and fluctuating…

Astrophysics · Physics 2009-11-24 Massimo Giovannini

The Eulerian space-time correlation of strong Magnetohydrodynamic (MHD) turbulence in strongly magnetized plasmas is investigated by means of direct numerical simulations of Reduced MHD turbulence and phenomenological modeling. Two new…

Solar and Stellar Astrophysics · Physics 2020-04-27 Jean C. Perez , Sofiane Bourouaine

Electron plasmas confined by an external magnetic field exhibit variations in a two-dimensional plane orthogonal to the confining magnetic field. A nonlinear fluid simulation code to investigate the properties of 2-D electron plasma wave…

Plasma Physics · Physics 2009-11-13 Dastgeer Shaikh , P. K. Shukla

A number of micro-scale biological flows are characterized by spatio-temporal chaos. These include dense suspensions of swimming bacteria, microtubule bundles driven by motor proteins, and dividing and migrating confluent layers of cells. A…

Fluid Dynamics · Physics 2017-08-02 Javier Urzay , Amin Doostmohammadi , Julia M. Yeomans

Multiscale correlation functions in high Reynolds number experimental turbulence and synthetic signals are investigated. Fusion Rules predictions as they arise from multiplicative, almost uncorrelated, random processes for the energy…

chao-dyn · Physics 2009-10-31 R. Benzi , L. Biferale , F. Toschi

We study the statistics of density for supersonic turbulence in a medium with magnetic pressure larger than the gaseous pressure. This study is motivated by molecular cloud research. Our simulations exhibit clumpy density structures, which…

Astrophysics · Physics 2009-11-10 A. Beresnyak , A. Lazarian , J. Cho

We present a brief introduction to the statistical properties of systems with large fluctuations. We point out that for such systems the relevant statistical quantities are scaling exponents and the nature of fluctuations is completely…

Astrophysics · Physics 2007-05-23 Francesco Sylos Labini , Andrea Gabrielli

An approach is suggested for treating multiscale fluctuations in macromolecular systems. The emphasis is on the statistical properties of such fluctuations. The approach is illustrated by a macromolecular system with mesoscopic fluctuations…

Chemical Physics · Physics 2012-08-07 V. I. Yukalov , E. P. Yukalova

Single-point measurements of fluctuations in the scrape-off layer of magnetized plasmas are generally found to be dominated by large-amplitude bursts which are associated with radial motion of blob-like structures. A stochastic model for…

Plasma Physics · Physics 2013-05-30 O. E. Garcia

Using the kinetic theory we discuss how the particle and energy densities of the quark-gluon plasma fluctuate in a space-time cell. The fluctuations in the equilibrium plasma and in that one from the early stage of ultrarelativistic…

Nuclear Theory · Physics 2008-11-26 Stanislaw Mrowczynski