Application of conservation laws to the asymptotic properties of hypersonic flow

The conservation laws involving mass, momentum, and energy are utilized for the derivation of a set of exact relations between the drag force on a body moving at hypersonic speeds through air and certain integral properties of the wake at great distances downstream. The above integral properties involve the surface integrals of the deviation of the hydrodynamical variables from their ambient values. The surface in question is a plane perpendicular to the wake axis. Explicitly, the relations state that all of the surface integrals just defined are proportional to the drag force with proportionality factors that are given functions of the ambient values of the hydrodynamical field variables. The results are valid if the plane cutting the wake is sufficiently far downstream that the deviations of the field variables are small relative to their ambient values everywhere on this plane and if irreversible processes are negligible there.