Thermal self-action effects of acoustic beam in a vibrationally relaxing gas

Thermal self-action of acoustic beam in a molecular gas with excited internal degrees of molecules' freedom, is studied. This kind of thermal self-action differs from that in a Newtonian fluid. Heating or cooling of a medium takes place due to transfer of internal vibrational energy. Equilibrium and non-equilibrium gases, which may be acoustically active, are considered. A beam in an acoustically active gas is self-focusing unlike a beam in a standard viscous gas. The self-action effects relating to wave beams containing shock fronts, are discussed. Stationary and non-stationary kinds of self-action are considered. (C) 2014 Elsevier Inc. All rights reserved.