Particle-assisted magnetohydrodynamics

Abstract:

We present a method which allows the kinetic effects of ions to be included in a magnetohydrodynamic model by representing plasma both as macroparticle ions and as a fluid. A novel aspect of the method is that plasma mass can be distributed arbitrarily between fluid and particles, thereby allowing kinetic effects to be included only in regions and times of interest. This allows a tradeoff to be made between computational cost of a model and accuracy of the physical description of plasma in different parts of the modeled system. It is also possible to have a smooth transition between fluid and kinetic physics in contrast to existing computational models in which a discontinuity in physics exists when transitioning between regions of different physical descriptions of plasma. By varying the fraction of plasma mass represented by particles it is also possible to gain insight into the physical effects required for and produced by various phenomena such as magnetic reconnection.