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Two-Fluid Plasma Lattice Boltzmann Model

Author: Jens von der Linden
Requested Type: Poster Only
Submitted: 2011-06-10 14:42:03

Co-authors: S. You

Contact Info:
University of Washington
Rm 120 AERB Box 352250
Seattle, WA   98195-2
USA

Abstract Text:
A two-fluid plasma model based on lattice Boltzmann methods [1] is developed and extended to include neutrals, free vacuum boundaries and embedded solid targets. Lattice Boltzmann methods model the motion of fluids by evolving distribution functions of a discretized Boltzmann-BGK equation over a very limited set of velocities (typically 9 in 2D or 19 in 3D). The macroscopic variables such as fluid density and momentum are recovered from the moments of the microscopic distribution functions over the limited set of velocity directions. The continuum equations can be recovered with a Chapmann-Enskog expansion. Similarly the electromagnetic fields are evolved as a lattice Boltzmann-BGK fluid with moments and equilibrium functions chosen such that multi-scale expansions retrieve Maxwell’s equations. The Lorentz force is implemented by discretizing the forcing term in the Boltzmann equation to couple plasma and electromagnetic lattices. The model does not approximate Ohm’s law and is stable for mass ratios ranging from 1 (resistive MHD) to 1820 (realistic two-fluid). Neutrals are added with a conventional lattice Boltzmann fluid which interacts with the plasma fluids through source and sink terms at the lattice nodes. Free vacuum boundaries are modeled with modified collisional operators of the plasma fluids to allow for free streaming in low density regions. Solid targets can be incorporated with simple bounce-back boundary collision operators or momentum conserving boundary collision operators. The two-fluid plasma lattice Boltzmann model will be compared with standard analytical solutions, other MHD and two-fluid CFD simulations. The novel numerical tool will support experimental interpretation of a new generalized plasma relaxation experiment and a study on the innovative use of plasma jets for deflection of space targets.

[1] M. Mendoza & J. D. Munoz. (2008.) Three-dimensional lattice Boltzmann model for magnetic reconnection. Phys. Rev. E 77, 026713

Characterization: A7,D3

Comments:
Please place with Setthivoine You's poster.

University of Washington

Workshop on Innovation in Fusion Science (ICC2011) and
US-Japan Workshop on Compact Torus Plasma
August 16-19, 2011
Seattle, Washington

ICC 2011