Energy budget in decaying compressible MHD turbulence

Yang, Yan; Wan, Minping; Matthaeus, W. H.; Chen, Shiyi

doi:10.1017/jfm.2021.199

“…These oscillations, as shown in Fig. 1, match fluctuations of the internal energy and are thus thought to be a consequence of exchanges between the kinetic plus magnetic energy and internal energy, as was already reported in Yang et al (2021), and initiated by the presence of waves. Using a linear fit, one can estimate the energy dissipation rate at the selected times: for Run I it is estimated at ∼ −0.047 and for Runs II and III at ∼ −0.087.…”

Section: Simulation Datasupporting

confidence: 79%

On Exact Laws in Incompressible Hall Magnetohydrodynamic Turbulence

Ferrand

¹

,

Galtier

²

,

Sahraoui

³

et al. 2019

ApJ

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A comparison is made between several existing exact laws in incompressible Hall magnetohydrodynamic (IHMHD) turbulence in order to show their equivalence, despite stemming from different mathematical derivations. Using statistical homogeneity, we revisit the law proposed by Hellinger et al. (2018) and show that it can be written, after being corrected by a multiplicative factor, in a more compact form implying only flux terms expressed as increments of the turbulent fields. The Hall contribution of this law is tested and compared to other exact laws derived by Galtier (2008) and Banerjee & Galtier (2017) using direct numerical simulations (DNSs) of three-dimensional electron MHD (EMHD) turbulence with a moderate mean magnetic field. We show that the studied laws are equivalent in the inertial range, thereby offering several choices on the formulation to use depending on the needs. The expressions that depend explicitly on a mean (guide) field may lead to residual errors in estimating the energy cascade rate ; however, we demonstrate that this guide field can be removed from these laws after mathematical manipulation. Therefore, it is recommended to use an expression independent of the mean guide field to analyze numerical or in-situ spacecraft data. arXiv:1905.06110v1 [physics.flu-dyn]

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“…Aspects that can play important roles include the sub or supersonic character of the system, the size of the β relative to unity, and the nature of any driving of the velocity field (e.g., is it the solenoidal velocity that is driven, the compressive component, or a combination). Simulation studies investigating various features of compressible MHD, such as energy transfer (both across scales Borovikov et al (2012) and between magnetic, internal energy, incompressible v, and compressive v components), and variance and spectral anisotropy have been reported on and these may provide starting points for understanding IHS Voyager observations (e.g., Ghosh and Matthaeus 1990;Lazarian 2002, 2003;Vestuto et al 2003;Carbone et al 2009;Kowal and Lazarian 2010;Banerjee and Galtier 2013;Oughton et al 2016;Grete et al 2017;Hadid et al 2017;Yang et al 2021). However, further studies are surely needed, including ones tailored to IHS conditions.…”

Section: Turbulence In the Inner Heliosheathmentioning

confidence: 99%

Turbulence in the Outer Heliosphere

Fraternale

¹

,

Adhikari

²

,

Fichtner

³

et al. 2022

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The solar wind (SW) and local interstellar medium (LISM) are turbulent media. Their interaction is governed by complex physical processes and creates heliospheric regions with significantly different properties in terms of particle populations, bulk flow and turbulence. Our knowledge of the solar wind turbulence nature and dynamics mostly relies on near-Earth and near-Sun observations, and has been increasingly improving in recent years due to the availability of a wealth of space missions, including multi-spacecraft missions. In contrast, the properties of turbulence in the outer heliosphere are still not completely understood. In situ observations by Voyager and New Horizons, and remote neutral atom measurements by IBEX strongly suggest that turbulence is one of the critical processes acting at the heliospheric interface. It is intimately connected to charge exchange processes responsible for the production of suprathermal ions and energetic neutral atoms. This paper reviews the observational evidence of turbulence in the distant SW and in the LISM, advances in modeling efforts, and open challenges.

show abstract

“…Aspects that can play important roles include the sub or supersonic character of the system, the size of the β relative to unity, and the nature of any driving of the velocity field (e.g., is it the solenoidal velocity that is driven, the compressive component, or a combination). Simulation studies investigating various features of compressible MHD, such as energy transfer (both across scales and between magnetic, internal energy, incompressible v, and compressive v components), and variance and spectral anisotropy have been reported on and these may provide starting points for understanding IHS Voyager observations (e.g., Ghosh and Matthaeus, 1990;Lazarian, 2002, 2003;Vestuto et al, 2003;Carbone et al, 2009;Kowal and Lazarian, 2010;Banerjee and Galtier, 2013;Oughton et al, 2016;Grete et al, 2017;Hadid et al, 2017;Yang et al, 2021). However, further studies are surely needed, including ones tailored to IHS conditions.…”

Section: Turbulence In the Inner Heliosheathmentioning

confidence: 99%

Turbulence in the outer heliosphere

Fraternale¹,

Adhikari²,

Fichtner³

et al. 2022

Preprint

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The solar wind (SW) and local interstellar medium (LISM) are turbulent media. Their interaction is governed by complex physical processes and creates heliospheric regions with significantly different properties in terms of particle populations, bulk flow and turbulence. Our knowledge of the solar wind turbulence nature and dynamics mostly relies on near-Earth and near-Sun observations, and has been increasingly improving in recent years due to the availability of a wealth of space missions, including multi-spacecraft missions. In contrast, the properties of turbulence in the outer heliosphere are still not completely understood. In situ observations by Voyager and New Horizons, and remote neutral atom measurements by IBEX strongly suggest that turbulence is one of the critical processes acting at the heliospheric interface. It is intimately connected to charge exchange processes responsible for the production of suprathermal ions and energetic neutral atoms. This paper reviews the observational evidence of turbulence in the distant SW and in the LISM, advances in modeling efforts, and open challenges.Keywords Turbulence • Solar wind • Interstellar medium • Heliosphere 1 Some definitions and nomenclature that will be used throughout in this paper are given: the Elsässer energies (Z ± ) 2 = z ± 2 /2, total turbulence energy density,Alfvén ratio r A = Eu/E b . Eu = δu 2 /2 and E b = δB 2 /(µ 0 ρ)/2 are the turbulent kinetic energy and magnetic energy densities in Alfvén units, respectively.

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Energy budget in decaying compressible MHD turbulence

Abstract: Abstract

Cited by 13 publications

References 131 publications

On Exact Laws in Incompressible Hall Magnetohydrodynamic Turbulence

On Exact Laws in Incompressible Hall Magnetohydrodynamic Turbulence

Turbulence in the Outer Heliosphere

Turbulence in the outer heliosphere

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