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Thermophysics and Aeromechanics

2002 year, number 1

On heat flux density and driving forces of diffusion in multicomponent ideal gas

Ya.m. Buzhdan
Institute of Inorganic Chemistry SB RAS, Novosibirsk, Russia
Pages: 127-135


It is shown for ideal gas considered within the framework of a continual mathematical model that the quantities accepted as the heat flux density often do not correspond to the conditions necessary for such a status. In this connection, the procedure for choosing a quantity accepted as the heat flux density is refined and corrected. The commonly accepted assumptions on the driving forces of the diffusion of medium components are corrected respectively. It is shown that neither the gradients of chemical potentials of the gas molecular components nor of their ratios to temperature are the driving forces for the diffusion transport of component masses relative to medium motion with mean mass velocity but the quantities - Grad[(R/i)lnpi], where pi is the partial pressure of the i-th molecular component of gas, i is its mole mass. The assumption is stated on the existence of such a type of the diffusion fluxes densities of components, to which the Onsager coefficients equal to zero of the mutual influence between the heat flux and diffusion fluxes correspond. The relations are obtained between the coefficients of multicomponent mutual diffusion and thermal diffusion ratios, which correspond to two variants of assumption realization.