The method of thermodynamics of irreversible processes with use of a principle of reciprocity Onsager deduces determining equations for thermodynamic flows diffusion and heat in a multicomponent mixtures of gases (in a kind of relations Stefan-Maxwell for multicomponent diffusion and expression appropriate to them for a full flow heat). Availability of exact relation Stefan-Maxwell has allowed phenomenological to receive: the formulas, connecting thermodiffusion of the ratio Kт β with coefficients thermal diffusion Dт β mixtures ; the formulas , connecting true λ and partial λ₀ coefficients diffusion Dα β through binary coefficients diffusion D αβ. All obtained formulas on a structure are completely identical to relations , given kinetic by the theory of multicomponent mixtures of one-nuclear gases of moderate density within the framework of the first approximation of a method Cherman - Enskog (comparison is conducted with results kinetic of the theory ,received in the known book Ferziger and Kaper).In difference from kinetic of the approach (up to the end developed only for gases of moderate density ,when potential of interaction between particles of a gas is known), macroscopic the approach is not connected with postulate of particular microscopic model of medium , therefore the results received in work have universal character and are suitable for the description of a wide class of mediums ( multinuclear mixtures of gases, dense gases, liquid solutions).

Mathematical modelling in actual problems of science and technics

Kolesnichenko Aleksandr Vladimirovich,  kolesn@keldysh.ru,  orcid.org/0000-0003-1416-5634,  KIAM RAS