Comparison for different gas flow models within the broad range of Knudsen numbers

A number of physical and mathematical models are considered, which use different levels for describing gas medium dynamics: kinetic, hydrodynamic (continuum model) and the level of moment equations. Several new models of hydrodynamic and moment levels are proposed. These models are analyzed on the basis of examples of degenerate flows within the Knudsen number range of $10^{-3}\dots10^{+3}$ from the point of view of their application for solving practical problems, associated with the variation of gas density within the broad gas density range. Kinetic S-model was used as a basis for the comparison of calculation results. Calculation results showed that the model of hydrodynamic level with corrected tensions, heat flows and boundary conditions secures gas medium parameters being the most close to the kinetic values.