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r m Potential minimum, m Potential well depth, /k B : K σ Collision diameter, m V Born-Mayer energy, /k B : K β Born-Mayer distance, m δ, γ Potential parameters C 6 Dispersion coefficient, /e 2 : 10 −50 m λ D Debye radius, m Collision cross sections Ω (l,s) Collision integral, m 2 Q Collision cross section, m 2 q Differential collision cross section, m 2 /rad χ Deflection angle, rad b Collision impact parameter, m A, B Fit constants (resonant charge transfer) Ψ, Ψ Digamma and trigamma function Universal Constants π 3.1415926535... Γ Euler constant, 0.5772156649... N A Avogadro number, 6.0221367 • 10 23 mol −1 k B Boltzmann constant, 1.380658 • 10 −23 J/K 0 Permittivity, 8.854187817 • 10 −12 As/Vm e Elementary charge, 1.60217733 • 10 −19 As m e Electron mass, 9.1093897 • 10 −31 kg Subscripts i, k Species index tr, int Translation, internal degrees of freedom q, o Quadrupole, octupole e, ion Electron, ion rct Resonant charge transfer R Reduced mass or relative velocity Superscripts * Reduced (dimensionless) property

A universally applicable model is presented for the calculation of the transport properties of ionized species in CFD simulations. A multicomponent mixture formulation and simple mixing rules are used to compute the transport coefficients of dissociated and ionized air from room temperature up to 30000 K at different pressures. Both formulations share little input data, which simplifies the handling of the transport model. The calculated binary diffusion coefficients are similar to the results of Levin et al.1–3 and Capitelli et al.4 The computed transport coefficients of the mixture are compared to the results of Gupta et al.5 A good agreement is found in the temperature range below 10000 K. At higher temperatures the results differ, because of the differences in the collision integrals of neutral‐ion and Coulomb interactions and because of the use of higher approximations of transport properties of electrons in the present model.

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