Chemical Derivatives and Elemental Transport Coefficients in Plasma Flows Near Local Equilibrium.

Elemental transport coefficients are extensively used for modeling chemically reacting and plasma flows when the proximity to local equilibrium is exploited to combine the ordinary transport coefficients into a few elemental coefficients. A deeper insight into the physics of chemically reacting flows near local equilibrium can be achieved by looking only at a reduced number of relevant parameters in the expression of the flow transport properties. A new technique to calculate chemical derivatives using an analytical method which strongly reduces computational effort and numerical errors is introduced. A general formalism for elemental diffusion velocities, heat flux and electric current for plasma flows near local equilibrium is then derived. An order of magnitude analysis shows how to identify the main contributions to the transport fluxes among: elemental fractions gradients, pressure or temperature gradients, electric field. The resulting theoretical framework is particularly suitable for numerical implementation. The present contribution aims to provide a summary of the theoretical framework described above. Numerical examples of chemical derivatives and elemental transport coefficients are given. Results are presented for a carbon dioxide mixture of practical interest for aerospace applications and atmospheric entry problems. [ABSTRACT FROM AUTHOR]