Variational multiscale method for nonequilibrium plasma flows

摘要: Abstract Plasmas at atmospheric or higher pressures, typically denoted as thermal plasmas, are partially ionized gases in which the high collision frequency among its constituents (molecules, atoms, ions, and electrons) causes intense transfer of electromagnetic to energy. Thermal plasma flows, often generated by electric arcs, core diverse technologies, such cutting, spraying, circuit breakers, lighting, fuel reforming, gasification. A computational nonequilibrium flow model based on Variational Multiscale (VMS) paradigm is presented. The described a compressible reactive fluid chemical equilibrium thermodynamic nonequilibrium. Two energy conservation equations, one for electrons other heavy-species, used describe deviations from Local Thermodynamic Equilibrium. Material properties (e.g., mass density, enthalpy, viscosity, electrical conductivity) vary several orders magnitude strongly nonlinear manner within these severely increases stiffness model. equations describing treated monolithic approach transient–advective–diffusive–reactive (TADR) transport system. An algebraic VMS Finite Element Method appropriate treatment general TADR problems method complemented with an intrinsic time-scales matrix definition fluid–electromagnetic sub-grid scales inexpensively discontinuity-capturing operator increase robustness handling large gradients. resulting discrete system solved generalized-alpha time-stepper together globalized inexact Newton–Krylov solver. verified incompressible, compressible, magnetohydrodynamic (MHD) benchmark problems, validated three canonical industrially-relevant flows: free-burning arc, transferred non-transferred arc flows torch.