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The Very Local Interstellar Medium (VLISM) contains clouds which consist of partially-ionized plasma. These clouds can be effectively diagnosed via high resolution optical and ultraviolet spectroscopy of the absorption lines they form in…

Astrophysics of Galaxies · Physics 2015-05-19 Steven R. Spangler , Allison H. Savage , Seth Redfield

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

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

Turbulent and vortical flows are ubiquitous and their characterization is crucial for the understanding of several natural and industrial processes. Among different techniques to study spatio-temporal flow fields, complex networks represent…

Fluid Dynamics · Physics 2020-11-04 Giovanni Iacobello , Luca Ridolfi , Stefania Scarsoglio

Vorticity in turbulent flows is often organized into complex geometries that influence the dynamics. We use a relatively novel approach to describe these geometries: that of obtaining segments of vortex lines embedded in the flow. This…

Fluid Dynamics · Physics 2023-01-18 Saumav Kapoor , Rama Govindarajan , Siddhartha Mukherjee

The elementary structures of turbulence, i.e., vortex tubes, are studied using velocity data obtained in laboratory experiments for boundary layers and duct flows at microscale Reynolds numbers 332-1934. While past experimental studies…

Fluid Dynamics · Physics 2009-11-13 H. Mouri , A. Hori

The small-scale statistical properties of velocity circulation in classical homogeneous and isotropic turbulent flows are assessed through a modeling framework that brings together the multiplicative cascade and the structural descriptions…

Fluid Dynamics · Physics 2022-08-17 Luca Moriconi , Rodrigo M. Pereira , Victor J. Valadão

The observational record of turbulence within the molecular gas phase of the interstellar medium is summarized. We briefly review the analysis methods used to recover the velocity structure function from spectroscopic imaging and the…

Astrophysics · Physics 2009-11-11 M. H. Heyer , C. Brunt

The numerical experiments of turbulence conducted by Gotoh et al. are analyzed precisely with the help of the formulae for the scaling exponents of velocity structure function and for the probability density function (PDF) of velocity…

Statistical Mechanics · Physics 2009-11-07 T. Arimitsu , N. Arimitsu

Identification and extraction of vortical structures and of waves in a disorganised flow is a mayor challenge in the study of turbulence. We present a study of the spatio-temporal behavior of turbulent flows in the presence of different…

Fluid Dynamics · Physics 2015-11-09 P. Clark di Leoni , P. J. Cobelli , P. D. Mininni

Based on the theoretical description of Position-Position-Velocity(PPV) statistics in Lazarian & Pogosyan(2000), we introduce a new technique called the Velocity Decomposition Algorithm(VDA) in separating the PPV fluctuations arising from…

Astrophysics of Galaxies · Physics 2021-04-14 Ka Ho Yuen , Ka Wai Ho , Alex Lazarian

Principal component analysis is a powerful statistical system to investigate the structure and dynamics of the molecular interstellar medium, with particular emphasis on the study of turbulence, as revealed by spectroscopic imaging of…

Astrophysics of Galaxies · Physics 2015-06-16 C. M. Brunt , M. H. Heyer

The multivariate tool of Principal Component Analysis (PCA) is applied to 23 fields in the FCRAO CO Survey of the Outer Galaxy. PCA enables the identification of line profile differences which are assumed to be generated from fluctuations…

Astrophysics · Physics 2009-11-07 Christopher M. Brunt , Mark H. Heyer

Complex spatial and temporal structures are inherent characteristics of turbulent fluid flows and comprehending them poses a major challenge. This comprehesion necessitates an understanding of the space of turbulent fluid flow…

Fluid Dynamics · Physics 2024-07-16 Tim Whittaker , Romuald A. Janik , Yaron Oz

Turbulent fluid dynamics typically involves excitations on many different length scales. Classical incompressible fluids can be cleanly represented in Fourier space enabling spectral analysis of energy cascades and other turbulence…

Quantum Gases · Physics 2022-11-02 Ashton S. Bradley , R. Kishor Kumar , Sukla Pal , Xiaoquan Yu

We compare velocity structure in the Polaris Flare molecular cloud at scales ranging from 0.015 pc to 20 pc to simulations of supersonic hydrodynamic and MHD turbulence computed with the ZEUS MHD code. We use several different statistical…

Astrophysics · Physics 2007-05-23 Volker Ossenkopf , Mordecai-Mark Mac Low

We perform a statistical analysis of experimental fully developed turbulence longitudinal velocity data in the Fourier space. We address the controversial issue of statistical intermittency of spatial Fourier modes by acting on the finite…

Statistical Mechanics · Physics 2007-05-23 L. Chevillard , N. Mazellier , C. Poulain , Y. Gagne , C. Baudet

Vortical structures of turbulence, i.e., vortex tubes and sheets, are studied using one-dimensional velocity data obtained in laboratory experiments for duct flows and boundary layers at microscale Reynolds numbers from 332 to 1934. We…

Fluid Dynamics · Physics 2009-11-13 H. Mouri , A. Hori , Y. Kawashima

Global spectral analysis (GSA) is used as a tool to test the accuracy of numerical methods with the help of canonical problems of convection and convection-diffusion equation which admit exact solutions. Similarly, events in turbulent flows…

Numerical Analysis · Mathematics 2022-03-21 Tapan K. Sengupta , Suman V. K. , Prasannabalaji Sundaram , Aditi Sengupta

We experimentally investigate the flow of a viscoelastic fluid in a parallel shear geometry at low Reynolds number. As the flow becomes unstable via a nonlinear subcritical instability, velocimetry measurements show non-periodic…

Fluid Dynamics · Physics 2017-07-26 Boyang Qin , Paulo E. Arratia