Skip to Main content Skip to Navigation
Journal articles

Generalized Fluid Models of the Braginskii Type

Abstract : Abstract Several generalizations of the well-known fluid model of Braginskii (1965) are considered. We use the Landau collisional operator and the moment method of Grad. We focus on the 21-moment model that is analogous to the Braginskii model, and we also consider a 22-moment model. Both models are formulated for general multispecies plasmas with arbitrary masses and temperatures, where all of the fluid moments are described by their evolution equations. The 21-moment model contains two “heat flux vectors” (third- and fifth-order moments) and two “viscosity tensors” (second- and fourth-order moments). The Braginskii model is then obtained as a particular case of a one ion–electron plasma with similar temperatures, with decoupled heat fluxes and viscosity tensors expressed in a quasistatic approximation. We provide all of the numerical values of the Braginskii model in a fully analytic form (together with the fourth- and fifth-order moments). For multispecies plasmas, the model makes the calculation of the transport coefficients straightforward. Formulation in fluid moments (instead of Hermite moments) is also suitable for implementation into existing numerical codes. It is emphasized that it is the quasistatic approximation that makes some Braginskii coefficients divergent in a weakly collisional regime. Importantly, we show that the heat fluxes and viscosity tensors are coupled even in the linear approximation, and that the fully contracted (scalar) perturbations of the fourth-order moment, which are accounted for in the 22-moment model, modify the energy exchange rates. We also provide several appendices, which can be useful as a guide for deriving the Braginskii model with the moment method of Grad.
Document type :
Journal articles
Complete list of metadata

https://hal.archives-ouvertes.fr/hal-03698172
Contributor : Thierry Passot Connect in order to contact the contributor
Submitted on : Saturday, June 18, 2022 - 7:15:27 AM
Last modification on : Thursday, August 4, 2022 - 4:55:40 PM

File

Hunana_2022_ApJS_260_26.pdf
Publisher files allowed on an open archive

Licence


Distributed under a Creative Commons Attribution 4.0 International License

Identifiers

Collections

Citation

P. Hunana, T. Passot, E. Khomenko, D. Martínez-Gómez, M. Collados, et al.. Generalized Fluid Models of the Braginskii Type. The Astrophysical Journal Supplement Series, IOPscience 2022, 260 (2), pp.26. ⟨10.3847/1538-4365/ac5044⟩. ⟨hal-03698172⟩

Share

Metrics

Record views

89

Files downloads

15