| 1. |
- Henri, P., et al.
(författare)
-
Nonlinear evolution of the magnetized Kelvin-Helmholtz instability : From fluid to kinetic modeling
- 2013
-
Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 20:10, s. 102118-
-
Tidskriftsartikel (refereegranskat)abstract
- The nonlinear evolution of collisionless plasmas is typically a multi-scale process, where the energy is injected at large, fluid scales and dissipated at small, kinetic scales. Accurately modelling the global evolution requires to take into account the main micro-scale physical processes of interest. This is why comparison of different plasma models is today an imperative task aiming at understanding cross-scale processes in plasmas. We report here the first comparative study of the evolution of a magnetized shear flow, through a variety of different plasma models by using magnetohydrodynamic (MHD), Hall-MHD, two-fluid, hybrid kinetic, and full kinetic codes. Kinetic relaxation effects are discussed to emphasize the need for kinetic equilibriums to study the dynamics of collisionless plasmas in non trivial configurations. Discrepancies between models are studied both in the linear and in the nonlinear regime of the magnetized Kelvin-Helmholtz instability, to highlight the effects of small scale processes on the nonlinear evolution of collisionless plasmas. We illustrate how the evolution of a magnetized shear flow depends on the relative orientation of the fluid vorticity with respect to the magnetic field direction during the linear evolution when kinetic effects are taken into account. Even if we found that small scale processes differ between the different models, we show that the feedback from small, kinetic scales to large, fluid scales is negligible in the nonlinear regime. This study shows that the kinetic modeling validates the use of a fluid approach at large scales, which encourages the development and use of fluid codes to study the nonlinear evolution of magnetized fluid flows, even in the collisionless regime.
|
|
| 2. |
- Lapenta, Giovanni, et al.
(författare)
-
SWIFF : Space weather integrated forecasting framework
- 2013
-
Ingår i: Journal of Space Weather and Space Climate. - : EDP Sciences. - 2115-7251. ; 3, s. A05-
-
Tidskriftsartikel (refereegranskat)abstract
- SWIFF is a project funded by the Seventh Framework Programme of the European Commission to study the mathematical-physics models that form the basis for space weather forecasting. The phenomena of space weather span a tremendous scale of densities and temperature with scales ranging 10 orders of magnitude in space and time. Additionally even in local regions there are concurrent processes developing at the electron, ion and global scales strongly interacting with each other. The fundamental challenge in modelling space weather is the need to address multiple physics and multiple scales. Here we present our approach to take existing expertise in fluid and kinetic models to produce an integrated mathematical approach and software infrastructure that allows fluid and kinetic processes to be modelled together. SWIFF aims also at using this new infrastructure to model specific coupled processes at the Solar Corona, in the interplanetary space and in the interaction at the Earth magnetosphere.
|
|
| 3. |
- Pierre, H., et al.
(författare)
-
Fluid and kinetic modelling of the magnetized Kelvin-Helmholtz instability
- 2020
-
Ingår i: ETC 2013 - 14th European Turbulence Conference. - : Zakon Group LLC.
-
Konferensbidrag (refereegranskat)abstract
- The nonlinear evolution of collisionless plasma flows is a multi-scale process where the energy is injected at large, fluid scales and dissipated at small, kinetic scales. Accurately modelling the global evolution of collisionless plasmas requires to take into account the main micro-scale physical processes of interest, in particular the kinetic effects. We concentrate here on the nonlinear evolution of the magnetized Kelvin-Helmholtz instability in collisionless plasmas. First, we will summarize recent works concerning fluid and kinetic modelling of the magnetized Kelvin-Helmholtz instability. Comparisons of different plasma models is today an imperative task aiming at understanding cross-scale processes in collisionless plasma turbulence. We then report new results of two dimensional fully kinetic (both electrons and ions are treated kinetically) simulations of the magnetized Kelvin-Helmholtz instability. We make use of the implicit Particle-In-Cell (PIC) code iPIC3D in 2D-3V configuration. In this work, we focus on the analysis of the effects of kinetic physics and compare results obtained with the full kinetic model to those obtained in the context of MHD and hybrid simulations. We discuss the space physics implications of the nonlinear saturation of the Kelvin-Helmholtz instability, in the context of the interactions between the solar wind and the Earth magnetosphere.
|
|
