Modeling techniques include (a) magnetohydrodynamics, in which the environment is treated as a fluid, (b) particle in cell, in which non-fluid interactions are handled within a cell and then cells are connected to describe the environment, (c) first principles, in which physical processes are in balance (or equilibrium) with one another, (d) semi-static modeling, in which a statistical or empirical relationship is described, or a combination of multiple methods.