SM31C-4205:
Poynting Flux-Conserving Boundary Conditions for Global MHD Models
Wednesday, 17 December 2014
Sheng Xi1, William Lotko1, Binzheng Zhang1, Oliver Brambles2, John Lyon1, Viacheslav G Merkin3 and Michael James Wiltberger4, (1)Dartmouth College, Hanover, NH, United States, (2)Thayer School of Engineering, Hanover, NH, United States, (3)The Johns Hopkins University, Laurel, MD, United States, (4)National Center for Atmospheric Research, High Altitude Observatory, Boulder, CO, United States
Abstract:
Poynting Flux-conserving boundary conditions that conserve low-frequency, magnetic field-aligned, electromagnetic energy flux across the low-altitude (or inner) boundary in global magnetospheric magnetohydrodynamics (MHD) models is presented. This method involves the mapping of both the potential from the ionosphere and the perpendicular magnetic field from the inner magnetosphere to the ghost cells of the computational domain. The single fluid Lyon-Fedder-Mobarry (LFM) model is used to verify this method. The comparisons of simulations using the standard hardwall boundary conditions of the LFM model and the flux-conserving boundary conditions show that the method reported here improves the transparency of the boundary for the flow of low-frequency (essentially DC) electromagnetic energy flux along field lines. As a consequence, the field-aligned DC Poynting flux just above the boundary is very nearly equal to the ionospheric Joule heating, as it should be if electromagnetic energy is conserved.
