| Abstract: | Computational methods are explored to characterize plasmas in propulsion and hypersonic applications, which are typically categorized as low-temperature plasmas. A full fluid model is developed where ions and electrons are treated as two different fluids that interact with each other through collisions and electromagnetic fields. Equations for the conservation of mass, momentum, and energy are solved for both fluids combined with the Poisson equation for the electric field. The computational model includes the Steger-Warming and global Lax-Friedrichs flux vector splitting schemes inside the domain and the monotonic upwind scheme for second order accuracy. At the boundaries, a kinetic form of the flux function is used. The kinetic fluxes are derived by taking moments of an assumed velocity distribution at the boundaries, which is generally a shifted Maxwellian. Kinetic fluxes are highly accurate as they account for the kinetic theory of gases, and also allow straightforward application of various kinds of boundary conditions without compro-mising the stability of the simulation. Two versions of the full fluid models are developed: one that solves an equation for the total electron energy and the other version that solves the electron temperature transport equation. While the former is a conservative formulation and gives accurate results in presence of shocks, the latter can be used to reduce computational time in case of collisional plasmas. The two versions of the full fluid models are verified on shock tube tests. A direct current magnetized plasma in a Hall effect thruster is simulated to study anomalous electron transport. The results are compared with drift-diffusion models, which neglect electron inertia. This comparison provides insights into the non-classical electron transport driven by the inertia term. It is shown that large velocity gradients can induce or enhance electron drift across magnetic field lines, a phenomenon that cannot be captured by the drift-diffusion theory. This drift is termed a shear-diamagnetic drift, as it displays conceptual similarity with the diamagnetic drift induced by the pressure difference. The full fluid model is also used to study the effect of the plasma sheath on the thermionic emission of electrons to explore the concept of electron transpiration cooling of the hypersonic vehicle leading edges. The full fluid model results are used to formulate the boundary conditions for hypersonic simulations that assume that the boundary lies at the sheath edge of the encapsulating plasma instead of the vehicle surface. A novel plasma sheath model assuming isentropic electrons is proposed to provide a high-fidelity, closed-form solution for the sheath. The results of this work provide deeper insights into the mechanisms for electron transport in cross-field devices and yield an improved understanding of the sheath dynamics for a better estimation of the plasma-surface interaction. The electronic version of this dissertation is accessible from https://hdl.handle.net/1969.1/198078 |
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