An implicit algorithm to simulate reaction chemistry in a plasma

Abstract

In an effort to establish the optimum conditions for depositing high-quality diamond films at high deposition rates using a plasma torch, modelling work has been focused on developing a realistic model for determining temperature, velocity and particle density distributions in the plasma jet. To enhance molecular decomposition, which favourably improves diamond synthesis, high-speed gas is passed through a supersonic anode nozzle. In the subsequent low-pressure chamber, the chemical reactions cannot follow the fast macroscopic translation, resulting in distributions of dissociated precursors that are far from chemical equilibrium. To simulate the finite rate chemistry, a generalized implicit multi-component algorithm is introduced and examined in the context of a two-dimensional computational model of a chemically reacting Ar- supersonic plasma jet. The scheme can be adapted to other plasma flows in which chemical non-equilibrium is encountered.

On the formal correctness of the reaction kinetics model and its solution in HV circuit breakers after current zero

“…by means of ( 12)) and the discontinuity in the numerical process. George et al [13] claim without giving reasons that the curve-fitting discrepancies may lead to numerical problems, such as negative number densities. In the numerical calculation of jump(f, t 0 ) by equation ( 12) of function f that is continuous in the sense of mathematical analysis the magnitude of jump(f, t 0 ) is approximately of the order of 10 −d × f (t 0 ).…”

“…the approximation, which in the model is, in fact, the function r k (T ), can be numerically continuous at point T 0 only by chance. If while determining the coefficients we require condition (13) to be fulfilled but we round the calculated coefficients such that after rounding we have…”

Evaluation of Computational Modeling of Electron Transpiration Cooling at High Enthalpies

“…The equilibrium constant for the electron-impact ionization reaction of argon is given in [17]. When the chemistry only has an electronimpact ionization reaction, such as with argon, the convergence of the CFD calculation is sensitive to avalanche ionization [15].…”

Comparisons of Computations with Experiments for Electron Transpiration Cooling at High Enthalpies

“…The equilibrium constant for the electron-impact ionization reaction of argon is given in Ref. 16. When the chemistry only has an electron-impact ionization reaction, such as with argon, the convergence of the CFD calculation is sensitive to avalanche ionization.…”