The physical processes modeled in MACH2Win include those essential to effective simulation of plasma pulsed power experiments at high energy densities, so long as the plasma may be assumed to remain quasi-neutral and displacement current effects may be neglected.

• The MHD includes the effect of the Lorentz and pressure forces, and magnetic field transport by fluid motion, resistive diffusion, and the Hall effect. All three components of magnetic field and velocity are included, subject only to the assumption of cylindrical or planar symmetry. MACH2 is thus capable of handling cylindrical problems with both toroidal and poloidal magnetic fields as well as swirling flow.
• The plasma is modeled as being in local thermodynamic equilibrium with separate electron and ion temperatures, using ideal gas or real equations of state chosen from the Los Alamos SESAME tables.
• Energy transport is modeled by radiation diffusion using a separate radiation temperature and by electron and ion thermal diffusion.
• Equilibrium radiation diffusion, a reduced model for energy transport appropriate for thick, high density plasma in which the radiation, electron, and ion temperatures are assumed to be in equilibrium, is also available. Also available is emissive cooling, another reduced model appropriate for thin low-density plasmas.
• Transport properties available include Spitzer resistivity and thermal conductivity, with their full tensor character caused by magnetic field effects. Other analytic models may be used, or these and other transport properties such as opacity and average ionization may be taken from the Los Alamos Sesame tables. User-created tabular equations of state and transport properties in SESAME format may also be used.
          

     The numerical algorithms in MACH2 are highly advanced. The numerically-generated boundary-fitted grid is Arbitrary Lagrangian/Eulerian, and may be dynamically adapted to capture flow features of particular interest. The spatial differencing is finite volume. The implicit hydrodynamic algorithm makes it possible to take time-steps three to ten times the explicit Courant limit, significantly increasing the smoothness and reducing the unimportant noise an explicit algorithm generates. The diffusive processes are also time-advanced implicitly using a multigrid elliptic/ parabolic solver. All of these algorithms are fully compatible with the multiblock architecture which makes possible MACH2's geometric flexibility.

Back