Multi-fluid simulations of the magnetosphere-ionosphere interaciotn and convection
Abstract
We have recently developed a multi-fluid version of the Lyon-Fedder-Mobarry (LFM) [Lyon, et al. 2004]. The MF-LFM builds upon the techniques used in the standard single fluid LFM to provide a multi-fluid code which is conservative, allows each species to move under its own force balance, and can handle shocks in individual species. The equations the multifluid LFM solves are the following: \begin{equation} {{∂ ρ_α}\over{∂ t}} + \DIVρ_α\V_α & = 0 \begin{equation} {{∂ ρ_α\Vα,\perp}\over{∂ t}} +{ρ_α\overρ}[ \DIVρ_α(\V_\perp + \V_∥)\V_\perp + ∇ P] & = - {ρ_α\overρ} [ěc{j}×ěc{B}] \begin{equation} {{∂ ρ_α \Vα,∥}\over{∂ t}} + \DIV(ρ_α(\V_\perp + Vα,∥)\Vα,∥) + ∇_∥( P_α + {{|n_α q_α|}\over{n_e}} P_e) & = -ναβ(Vα,∥- \Vβ,∥) \begin{equation} {{∂{\mathcal E}_α}\over{∂ t}} + \DIV((\V_\perp + \Vα,∥)({ρ_α\over 2}(\V_\perp2+\Vα,∥2) + {γ\over{γ-1}}P_α) & = {ρ_α\overρ}ěc{j}·ěc{E} \begin{equation} {{∂ ěc{B}}\over{∂ t}} & = - \CURL(\V × ěc{B}) where the first four equations are the continuity, perpendicular momentum, parallel momentum, and plasma energy for each of the species. The final equation is Faraday's Law for ideal MHD. The equation for the parallel momentum shows that motion in the parallel direction is independent of the other species. The term on the RHS is a phenomenological drag term added to allow for cases in which counter-streaming ions might produce plasma instabilities that couple different species together. It is similar to an anomalous resisitivity term added to the induction equation. In general, it is set explicity to zero. The perpendicular momentum equations state that all the species share the same acceleration in that direction. We apply this new code to simpified problems involving localized oxygen outflow from the ionosphere. We will discuss the trajecory of the outflowing oxygen and its subsequent convection and energization within the magnetosphere. In addition we will discuss how the basic multi-fluid algorithm can be extended to include the effects of gradient, curvature and diamagnetic drifts. [Lyon et al., 2004] J.G. Lyon, J.A. Fedder and C.M. Mobabry, J. Atmos. and Solar Terr. Phys., 66, 1333-1350, 2004.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFMSM44A..04L
- Keywords:
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- 2736 Magnetosphere/ionosphere interactions (2431);
- 2753 Numerical modeling;
- 2760 Plasma convection (2463)