Browsing by Subject "turbulence"

Now showing items 1-20 of 37

  • Anomalous transport of cosmic rays in a nonlinear diffusion model

    Litvinenko, Yuri E.; Fichtner, Horst; Walter, Dominik (The American Astronomical Society, 2017)
    We investigate analytically and numerically the transport of cosmic rays following their escape from a shock or another localized acceleration site. Observed cosmic-ray distributions in the vicinity of heliospheric and ...
  • Assessment of the performance of a turbulence closure model: along the tidally-influenced Kaipara River to the estuary, NZ

    Dejeans, Berengere S.; Mullarney, Julia C.; MacDonald, Iain T.; Reeve, Glen M. (2017)
    The success of many coastal management projects hinges on the ability to predict the dispersal and settling of sediment particles. Hydrodynamic models have enabled the efficient simulation of sediment transport scenarios ...
  • Coronal heating by magnetohydrodynamic turbulence driven by reflected low-frequency waves

    Matthaeus, William H.; Zank, Gary P.; Oughton, Sean; Mullan, D. J.; Dmitruk, Pablo (IOP PUBLISHING LTD, 1999)
    A candidate mechanism for the heating of the solar corona in open field line regions is described. The interaction of Alfvén waves, generated in the photosphere or chromosphere, with their reflections and the subsequent ...
  • Coronal heating distribution due to low-frequency, wave-driven turbulence

    Dmitruk, Pablo; Matthaeus, William H.; Milano, L. J.; Oughton, Sean; Zank, Gary P.; Mullan, D. J. (University of Chicago Press, 2002)
    The heating of the lower solar corona is examined using numerical simulations and theoretical models of magnetohydrodynamic turbulence in open magnetic regions. A turbulent energy cascade to small length scales perpendicular ...
  • Cross-helically forced and decaying hydromagnetic turbulence

    Brandenburg, Axel; Oughton, Sean (WILEY-V C H VERLAG GMBH, 2018)
    We study the evolution of kinetic and magnetic energy spectra in magnetohydrodynamic flows in the presence of strong cross helicity. For forced turbulence, we find a weak inverse transfer of kinetic energy toward the ...
  • Deposition gradients across mangrove fringes

    Horstman, Erik M.; Mullarney, Julia C.; Bryan, Karin R.; Sandwell, Dean R. (2017)
    Observations in a mangrove in the Whangapoua Harbour, New Zealand, have shown that deposition rates are greatest in the fringing zone between the tidal flats and the mangrove forest, where the vegetation is dominated by a ...
  • Directional alignment and non-Gaussian statistics in solar wind turbulence

    Osman, Kareem T.; Wan, Minping; Matthaeus, William H.; Breech, Ben; Oughton, Sean (IOP Publishing, 2011)
    The magnetic and velocity field fluctuations in magnetohydrodynamic turbulence can be characterized by their directional alignment and induced electric field. These manifest as coherent spatial correlations which are ...
  • Effects of a small-bladed macroalgal canopy on benthic boundary layer dynamics: implications for nutrient transport

    Kregting, Louise T.; Stevens, Craig L.; Cornelisen, Christopher D.; Pilditch, Conrad A.; Hurd, Catriona L. (INTER Research Science Publ, 2011)
    Field and laboratory velocity profiles were used to quantify boundary layer dynamics within communities of a small (<0.2 m tall), dense canopy-forming seaweed Adamsiella chauvinii (Rhodophyta) in a soft-sediment habitat ...
  • Focused acceleration of cosmic-ray particles in non-uniform magnetic fields

    Litvinenko, Yuri E.; Schlickeiser, Reinhard (The American Astronomical Society, 2011)
    The Fokker–Planck equation for cosmic-ray particles in a spatially varying guide magnetic field in a turbulent plasma is analyzed. An expression is derived for the mean rate of change of particle momentum, caused by the ...
  • General second-rank correlation tensors for homogeneous magnetohydrodynamic turbulence

    Oughton, Sean; Rädler, K.-H.; Matthaeus, William H. (The American Physical Society, 1997)
    The properties and structure of second-order (Cartesian) correlation tensors are derived for the general case of two solenoidal random vector fields. The theory is intended to describe homogeneous magnetohydrodynamic ...
  • Heating of the solar wind with electron and proton effects

    Breech, Ben; Cranmer, Steven R.; Matthaeus, William H.; Kasper, Justin C.; Oughton, Sean; Maksimovic, M.; Issautier, K.; Meyer-Vernet, N.; Moncuquet, M.; Pantellini, F. (American Institute of Physics, 2010)
    We examine the effects of including effects of both protons and electrons on the heating of the fast solar wind through two different approaches. In the first approach, we incorporate the electron temperature in an MHD ...
  • Impact of Hall effect on energy decay in magnetohydrodynamic turbulence

    Matthaeus, William H.; Dmitruk, Pablo; Smith, D.; Ghosh, S.; Oughton, Sean (American Geophysical Union, 2003)
    We examine numerically the influence of Hall effect corrections to Ohm's law upon the decay of homogeneous compressible magnetohydrodynamic turbulence and conclude that there are no significant differences in global decay ...
  • Investigation of intermittency in magnetohydrodynamics and solar wind turbulence: scale-dependent kurtosis

    Wan, Minping; Osman, Kareem T.; Matthaeus, William H.; Oughton, Sean (IOP PUBLISHING LTD, 2012)
    The behavior of scale-dependent (or filtered) kurtosis is studied in the solar wind using magnetic field measurements from the ACE and Cluster spacecraft at 1 AU. It is also analyzed numerically with high-resolution ...
  • Lake-size dependency of wind shear and convection as controls on gas exchange

    Read, Jordan S.; Hamilton, David P.; Desai, Ankur R.; Rose, Kevin; MacIntyre, Sally; Lenters, John D.; Smyth, Robyn L.; Hanson, Paul C.; Cole, Jonathan J.; Staehr, Peter A.; Rusak, James A.; Pierson, Donald C.; Brookes, Justin D.; Laas, Alo; Wu, Chin H. (American Geophysical Union (AGU), 2012)
    High-frequency physical observations from 40 temperate lakes were used to examine the relative contributions of wind shear (u∗) and convection (w∗) to turbulence in the surface mixed layer. Seasonal patterns of u∗ and w∗ ...
  • Local anisotropy, higher order statistics, and turbulence spectra

    Matthaeus, William H.; Servidio, Sergio; Dmitruk, Pablo; Carbone, V.; Oughton, Sean; Wan, Minping; Osman, Kareem T. (IOP PUBLISHING LTD, 2012)
    Correlation anisotropy emerges dynamically in magnetohydrodynamics (MHD), producing stronger gradients across the large-scale mean magnetic field than along it. This occurs both globally and locally, and has significant ...
  • Magnetic field line random walk in models and simulations of reduced magnetohydrodynamic turbulence

    Snodin, A. P.; Ruffolo, D.; Oughton, Sean; Servidio, Sergio; Matthaeus, William H. (IOP PUBLISHING LTD, 2013)
    The random walk of magnetic field lines is examined numerically and analytically in the context of reduced magnetohydrodynamic (RMHD) turbulence, which provides a useful description of plasmas dominated by a strong mean ...
  • MHD‐driven kinetic dissipation in the solar wind and corona

    Leamon, R. J.; Matthaeus, William H.; Smith, Charles W.; Zank, Gary P.; Mullan, D. J.; Oughton, Sean (University of Chicago Press, 2000)
    Mechanisms for the deposition of heat in the lower coronal plasma are discussed, emphasizing recent attempts to reconcile the fluid and kinetic perspectives. Structures at magnetohydrodynamic (MHD) scales may drive a ...
  • Modeling focused acceleration of cosmic-ray particles by stochastic methods

    Armstrong, Craig Keith; Litvinenko, Yuri E.; Craig, Ian J.D. (Institute of Physics -IOP, 2012)
    Schlickeiser & Shalchi suggested that a first-order Fermi mechanism of focused particle acceleration could be important in several astrophysical applications. In order to investigate focused acceleration, we express the ...
  • Modeling sunspot and starspot decay by turbulent erosion

    Litvinenko, Yuri E.; Wheatland, M.S. (The American Astronomical Society, 2015-02-20)
    Disintegration of sunspots (and starspots) by fluxtube erosion, originally proposed by Simon and Leighton, is considered. A moving boundary problem is formulated for a nonlinear diffusion equation that describes the sunspot ...
  • Nonlinear and linear timescales near kinetic scales in solar wind turbulence

    Matthaeus, William H.; Oughton, Sean; Osman, Kareem T.; Servidio, Sergio; Wan, Minping; Gary, S.P.; Shay, M.A.; Valentini, F.; Roytershteyn, V.; Karimabadi, H.; Chapman, S.C. (American Astronomical Society, 2014-08-01)
    The application of linear kinetic treatments to plasma waves, damping, and instability requires favorable inequalities between the associated linear timescales and timescales for nonlinear (e.g., turbulence) evolution. In ...