Invariant form and asymptotic properties of a generalized quasi-gasdynamic system

Two interrelated systems of equations, quasi-gasdynamic and generalized quasi-gasdynamic, obtained by the moment averaging of model kinetic equations of the Boltzmann kind, are examined. A derivation of the two systems of equations in arbitrary curvilinear coordinates is presented. The smooth solutions of the generalized quasi-gasdynamic system agree, within a certain error, with the Navier-Stokes equations. In the stationary case, a boundary layer approximation is obtained for quasi-gasdynamic equations, and the entropy equation is proved.