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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2009
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_1070664X_v16_n6_p_Dmitruk http://hdl.handle.net/20.500.12110/paper_1070664X_v16_n6_p_Dmitruk |
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paper:paper_1070664X_v16_n6_p_Dmitruk2023-06-08T16:04:36Z Waves and turbulence in magnetohydrodynamic direct numerical simulations Dmitruk, Pablo Ariel 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. 2009 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_1070664X_v16_n6_p_Dmitruk 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, Pablo Ariel 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. |
| author |
Dmitruk, Pablo Ariel |
| author_facet |
Dmitruk, Pablo Ariel |
| author_sort |
Dmitruk, Pablo Ariel |
| 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 |
| publishDate |
2009 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_1070664X_v16_n6_p_Dmitruk http://hdl.handle.net/20.500.12110/paper_1070664X_v16_n6_p_Dmitruk |
| work_keys_str_mv |
AT dmitrukpabloariel wavesandturbulenceinmagnetohydrodynamicdirectnumericalsimulations |
| _version_ |
1768544376458313728 |