Approximate equations for transport fluxes in multicomponent mixtures

Approximate equations for transport fluxes in multicomponent mixtures 

Despite the complicated nature of the formulations of the transport fluxes discussed above, the results of computations which use these equations do not differ much (e.g., less than 5-10% in the steady-state burning velocity of 

The equation (3.28) for the pressure tensor remains unchanged. The coefficient of viscosity is given by the following equations  

The approximations to the diffusive fluxes involve a slightly different formulation from Eq. (3.32) for the diffusion velocities. Equation (3.32) itself, together with the solutions of Eqs. (3.25c), can be rearranged to give the Stefan-Maxwell diffusion equations (Muckenfuss and Curtiss, 1958 Monchick, Munn, and Mason, 1966 Dixon-Lewis, 1968). If the thermal diffusion terms are neglected these equations become, in the first approximation. 

Substituting back for V in Eq. (3.65) then leads to the result used by Hirschfelder and Curtiss (1949) 

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