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We extend a two-component model for the evolution of fluctuations in the solar wind plasma so that it is fully three-dimensional (3D) and also coupled self-consistently to the large-scale magnetohydrodynamic (MHD) equations describing the…

Solar and Stellar Astrophysics · Physics 2016-12-14 Tobias Wiengarten , Sean Oughton , Eugene Engelbrecht , Horst Fichtner , Jens Kleimann , Klaus Scherer

We present velocity spectra measured in three cryogenic liquid 4He steady flows: grid and wake flows in a pressurized wind tunnel capable of achieving mean velocities up to 5 m/s at temperatures above and below the superfluid transition,…

Current-voltage measurements of type-II superconductors are described by a coarse-grained model of superconducting vortex dynamics. We find that the power spectra of the voltage fluctuations, and the noise power, are related to the large…

Statistical Mechanics · Physics 2007-05-23 Kevin E. Bassler , Joern Davidsen , Maya Paczuski

We use momentum transfer arguments to predict the friction factor $f$ in two-dimensional turbulent soap-film flows with rough boundaries (an analogue of three-dimensional pipe flow) as a function of Reynolds number Re and roughness $r$,…

Fluid Dynamics · Physics 2015-05-13 Nicholas Guttenberg , Nigel Goldenfeld

The spectrum of turbulence in superfluid liquid is modified by the nonlinear energy dissipation caused by the mutual friction between quantized vortices and the normal component of the liquid. In some region of two Reynolds parameters…

Chaotic Dynamics · Physics 2009-11-10 Victor S. L'vov , Sergey V. Nazarenko , Grigory E. Volovik

We present a direct numerical simulation (DNS) study of pseudo-turbulence in buoyancy driven bubbly flows for a range of Reynolds ($\Rey$) and Atwood ($\At$) numbers. We study the probability distribution function of the horizontal and…

Fluid Dynamics · Physics 2020-02-19 Vikash Pandey , Rashmi Ramadugu , Prasad Perlekar

We find strong evidence for intermittency in forced two dimensional (2D) turbulence in a flowing soap film experiment. In the forward enstrophy cascade the structure function scaling exponents are nearly indistinguishable from 3D studies.…

Chaotic Dynamics · Physics 2007-05-23 W. Brent Daniel , Maarten A. Rutgers

Many fluid-dynamical systems met in nature are quasi-two-dimensional: they are constrained to evolve in approximately two dimensions with little or no variation along the third direction. This has a drastic effect in the flow evolution…

Fluid Dynamics · Physics 2024-11-14 Alexandros Alexakis

By analyzing hot-wire velocity data taken in an open channel flow, an unambiguous definition of surface-layer thickness is here provided in terms of the cross-over scale between backward and forward energy fluxes. It is shown that the…

Fluid Dynamics · Physics 2016-11-18 Guido Troiani , Francesco Cioffi , Angelo Olivieri , Carlo Massimo Casciola

We study the two dimensional (2D) stochastic Navier Stokes (SNS) equations in the inertial limit of weak forcing and dissipation. The stationary measure is concentrated close to steady solutions of the 2D Euler equation. For such inertial…

Chaotic Dynamics · Physics 2009-11-13 Freddy Bouchet , Eric Simonnet

We consider the two-dimensional (2D) flow in a flat free-slip surface that bounds a three-dimensional (3D) volume in which the flow is turbulent. The equations of motion for the two-dimensional flow in the surface are neither compressible…

Chaotic Dynamics · Physics 2009-11-07 Bruno Eckhardt , Joerg Schumacher

Fluctuations in the flow velocity and magnetic fields are ubiquitous in the Solar System. These fluctuations are turbulent, in the sense that they are disordered and span a broad range of scales in both space and time. The study of solar…

Solar and Stellar Astrophysics · Physics 2016-02-04 F. Fraternale , L. Gallana , M. Iovieno , M. Opher , J. D. Richardson , D. Tordella

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…

Turbulent flows in a thin layer can develop an inverse energy cascade leading to spectral condensation of energy when the layer height is smaller than a certain threshold. These spectral condensates take the form of large-scale vortices in…

Fluid Dynamics · Physics 2019-09-11 Adrian van Kan , Takahiro Nemoto , Alexandros Alexakis

By searching through more than 10 satellite-years of THEMIS and Cluster data, three reliable examples of parallel electric field turbulence in the undisturbed solar wind have been found. The perpendicular and parallel electric field spectra…

Space Physics · Physics 2013-04-18 F. S. Mozer , C. H. K. Chen

Measurements of atmospheric winds in the mesoscale range (10-500 km) reveal remarkably universal spectra with the $k^{-5/3}$ power law. Despite initial expectations of the inverse energy cascade, as in two-dimensional (2D) turbulence,…

Fluid Dynamics · Physics 2008-05-06 H. Xia , H. Punzmann , G. Falkovich , M. Shats

The transport equations for velocity variances are investigated using data from DNS of incompressible channel flows at $Re_\tau$ up to 5200. Each term in the transport equation has been spectrally decomposed to expose the contribution of…

Fluid Dynamics · Physics 2018-12-26 Myoungkyu Lee , Robert D. Moser

In active Brownian motion, an internal propulsion mechanism interacts with translational and rotational thermal noise and other internal fluctuations to produce directed motion. We derive the distribution of its extreme fluctuations and…

Statistical Mechanics · Physics 2016-05-04 Patrick Pietzonka , Kevin Kleinbeck , Udo Seifert

We consider a simple fluid confined between two parallel walls (substrates), separated by a distance L. The walls exert competing surface fields so that one wall is attractive and may be completely wet by liquid (it is solvophilic) while…

Soft Condensed Matter · Physics 2014-09-01 Maria C. Stewart , Robert Evans

Hydraulic jumps are oftentimes encountered in natural and human-made environments. The transition from supercritical to subcritical flow involves large energy dissipation rates and substantial air entrainment, preventing the use of…

Fluid Dynamics · Physics 2022-04-26 Matthias Kramer , Daniel Valero