Applicability of the theory of continuous media to unsteady viscous gas flows
Abstract
The idealized medium conventionally assumed in gas dynamics possesses the property of continuity or compactness, whereas real gases are composed of particles discretely distributed in space. In the present paper, it is pointed out that for unsteady viscous gas flows, the Knudsen number (i.e., the ratio of the molecular mean free path to a certain linear scale defined by the nonstationarity of the flow) may figure as the continuity criterion, rather than the ratio of the mean time between molecular collisions to the characteristic time of the problem.
 Publication:

TsAGI Uchenye Zapiski
 Pub Date:
 1977
 Bibcode:
 1977ZaTsA...8...66Z
 Keywords:

 Continuum Mechanics;
 Gas Dynamics;
 Unsteady Flow;
 Viscous Flow;
 Boundary Layers;
 Intermolecular Forces;
 Knudsen Flow;
 Mean Free Path;
 Reynolds Number;
 Strouhal Number;
 Fluid Mechanics and Heat Transfer