Waves and turbulence in magnetohydrodynamic direct numerical simulations

Direct numerical simulations of the incompressible MHD equations with a uniform background magnetic field in a turbulent regime are performed to assess the relative importance of broadband turbulent fluctuations and wavelike fluctuations that are associated with an Alfv́n wave dispersion relation. T...

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Autores principales: Dmitruk, P., Matthaeus, W.H.
Formato: JOUR
Materias:
Complex behavior
Eulerian
Frequency domains
Frequency spectra
Full spectrum
Leading orders
Linear solution
Mean magnetic field
MHD equations
N-waves
Nonlinear simulations
Nonlinear transfer
Perturbation theory
Relative importance
Strong turbulence
Turbulent fluctuation
Turbulent regime
Wave number modes
Wave numbers
Direct numerical simulation
Magnetic fields
Perturbation techniques
Signal to noise ratio
Spectroscopy
Turbulence
Wave equations
Power spectrum
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_1070664X_v16_n6_p_Dmitruk
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id todo:paper_1070664X_v16_n6_p_Dmitruk
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spelling todo:paper_1070664X_v16_n6_p_Dmitruk2023-10-03T16:02:31Z Waves and turbulence in magnetohydrodynamic direct numerical simulations Dmitruk, P. Matthaeus, W.H. Complex behavior Eulerian Frequency domains Frequency spectra Full spectrum Leading orders Linear solution Mean magnetic field MHD equations N-waves Nonlinear simulations Nonlinear transfer Perturbation theory Relative importance Strong turbulence Turbulent fluctuation Turbulent regime Wave number modes Wave numbers Direct numerical simulation Magnetic fields Perturbation techniques Signal to noise ratio Spectroscopy Turbulence Wave equations Power spectrum Direct numerical simulations of the incompressible MHD equations with a uniform background magnetic field in a turbulent regime are performed to assess the relative importance of broadband turbulent fluctuations and wavelike fluctuations that are associated with an Alfv́n wave dispersion relation. The focus is on properties of the fluctuations in the frequency domain. Eulerian frequency spectra and individual wave number mode frequency spectra show the presence of peaks at the corresponding Alfv́n wave frequencies for full nonlinear simulations in a turbulent regime. The peaks are however broad and their power content is compared to the power in the full spectrum as well as a signal to noise ratio is defined and quantified for different values of the background magnetic field. The ratio of power in Alfv́n waves to the power in the rest of the spectrum is also quantified and is found to be small for different values of the mean magnetic field. Individual modes in time show a much more complex behavior than that could be expected for linear solutions. Also, nonlinear transfer of energy is evidenced by the existence of peaks at wave numbers perpendicular to the mean magnetic field. Implications are discussed for theories of strong turbulence as well as perturbation theories that assume the leading order behavior is that of propagating Alfv́n waves. © 2009 American Institute of Physics. Fil:Dmitruk, P. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_1070664X_v16_n6_p_Dmitruk
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Complex behavior
Eulerian
Frequency domains
Frequency spectra
Full spectrum
Leading orders
Linear solution
Mean magnetic field
MHD equations
N-waves
Nonlinear simulations
Nonlinear transfer
Perturbation theory
Relative importance
Strong turbulence
Turbulent fluctuation
Turbulent regime
Wave number modes
Wave numbers
Direct numerical simulation
Magnetic fields
Perturbation techniques
Signal to noise ratio
Spectroscopy
Turbulence
Wave equations
Power spectrum
spellingShingle Complex behavior
Eulerian
Frequency domains
Frequency spectra
Full spectrum
Leading orders
Linear solution
Mean magnetic field
MHD equations
N-waves
Nonlinear simulations
Nonlinear transfer
Perturbation theory
Relative importance
Strong turbulence
Turbulent fluctuation
Turbulent regime
Wave number modes
Wave numbers
Direct numerical simulation
Magnetic fields
Perturbation techniques
Signal to noise ratio
Spectroscopy
Turbulence
Wave equations
Power spectrum
Dmitruk, P.
Matthaeus, W.H.
Waves and turbulence in magnetohydrodynamic direct numerical simulations
topic_facet Complex behavior
Eulerian
Frequency domains
Frequency spectra
Full spectrum
Leading orders
Linear solution
Mean magnetic field
MHD equations
N-waves
Nonlinear simulations
Nonlinear transfer
Perturbation theory
Relative importance
Strong turbulence
Turbulent fluctuation
Turbulent regime
Wave number modes
Wave numbers
Direct numerical simulation
Magnetic fields
Perturbation techniques
Signal to noise ratio
Spectroscopy
Turbulence
Wave equations
Power spectrum
description Direct numerical simulations of the incompressible MHD equations with a uniform background magnetic field in a turbulent regime are performed to assess the relative importance of broadband turbulent fluctuations and wavelike fluctuations that are associated with an Alfv́n wave dispersion relation. The focus is on properties of the fluctuations in the frequency domain. Eulerian frequency spectra and individual wave number mode frequency spectra show the presence of peaks at the corresponding Alfv́n wave frequencies for full nonlinear simulations in a turbulent regime. The peaks are however broad and their power content is compared to the power in the full spectrum as well as a signal to noise ratio is defined and quantified for different values of the background magnetic field. The ratio of power in Alfv́n waves to the power in the rest of the spectrum is also quantified and is found to be small for different values of the mean magnetic field. Individual modes in time show a much more complex behavior than that could be expected for linear solutions. Also, nonlinear transfer of energy is evidenced by the existence of peaks at wave numbers perpendicular to the mean magnetic field. Implications are discussed for theories of strong turbulence as well as perturbation theories that assume the leading order behavior is that of propagating Alfv́n waves. © 2009 American Institute of Physics.
format JOUR
author Dmitruk, P.
Matthaeus, W.H.
author_facet Dmitruk, P.
Matthaeus, W.H.
author_sort Dmitruk, P.
title Waves and turbulence in magnetohydrodynamic direct numerical simulations
title_short Waves and turbulence in magnetohydrodynamic direct numerical simulations
title_full Waves and turbulence in magnetohydrodynamic direct numerical simulations
title_fullStr Waves and turbulence in magnetohydrodynamic direct numerical simulations
title_full_unstemmed Waves and turbulence in magnetohydrodynamic direct numerical simulations
title_sort waves and turbulence in magnetohydrodynamic direct numerical simulations
url http://hdl.handle.net/20.500.12110/paper_1070664X_v16_n6_p_Dmitruk
work_keys_str_mv AT dmitrukp wavesandturbulenceinmagnetohydrodynamicdirectnumericalsimulations
AT matthaeuswh wavesandturbulenceinmagnetohydrodynamicdirectnumericalsimulations
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