HR: 10:50h
AN: SM32A-02    [Abstracts]
TI: Entropy Conservation in Simulations of Magnetic Reconnection
AU: * Birn, J
EM: jbirn@lanl.gov
AF: Los Alamos National Laboratory, MS D466, PO Box 1663, Los Alamos, NM 87545 United States
AU: Hesse, M
EM: hesse@gsfc.nasa.gov
AF: NASA/Goddard Space Flight Center, Code 696, Greenbelt, MD 20771 United States
AB: A crucial element in the physics of reconnection is the local breakdown of the frozen-in field approximation that governs ideal MHD. However, there are other approximations included in ideal MHD, which might also be expected to break down when reconnection is initiated, specifically the conservation of entropy. We use the "Newton challenge" problem of forced current sheet thinning and reconnection to compare entropy conservation in a resistive MHD simulation with a particle-in-cell simulation. When the resistivity is strongly localized in the MHD simulation, the global conservation of entropy in magnetic flux tubes undergoing reconnection is surprisingly similar between fluid and particle simulations. This explains why the final configurations are also very similar, despite the fact that the pressure distributions change drastically and that particle simulations include pressure anisotropy, waves, and dissipation mechanisms different from the resistive fluid model. It further indicates that Joule dissipation is highly localized.
DE: 2744 Magnetotail
DE: 2753 Numerical modeling
DE: 2764 Plasma sheet
DE: 7827 Kinetic and MHD theory
DE: 7835 Magnetic reconnection
SC: SPA-Magnetospheric Physics [SM]
MN: 2005 Joint Assembly