Accession Number : AD0684571

Title :   AN APPROXIMATE METHOD FOR ANALYZING NONEQUILIBRIUM ACOUSTIC PHENOMENA WITH APPLICATION TO DISCRETE RADIATION-DRIVEN WAVES,

Corporate Author : STANFORD UNIV CALIF DEPT OF AERONAUTICS AND ASTRONAUTICS

Personal Author(s) : Cogley,Allen C.

Report Date : FEB 1968

Pagination or Media Count : 267

Abstract : A study is made of the interaction between radiative heat transfer and fluid flow in the acoustic approximation. The work introduces a new analytical technique for handling one-dimensional radiative transfer in a nongrey gas near equilibrium. Radiative effects are treated on the basis of the quasi-equilibrium hypothesis, and for simplicity the gas is assumed to be perfect. A nongrey exponential approximation is made to obtain a differential formulation. Combination of the resulting simplified transfer equation with the gas-dynamic equations gives a fifth-order partial differential equation in a perturbation potential. An approximate mathematical method for solving linear wave-propagation problems in the presence of nonequilibrium processes is then employed. The solutions of several previously considered problems are obtained with this approach. The previously unsolved problem of the gas-dynamic response to a step input of radiation from a stationary black wall has also been solved. As shown by the solution, the radiative transfer gives rise initially to a compression-expansion wave in the gas, with the wavefront controlled by radiation. The disturbance at the wavefront, though caused directly by radiative transfer of small time, eventually outruns the wall radiation and becomes a modified-classical disturbance propagating away from the wall at the isentropic speed of sound. (Author)

Descriptors :   (*GAS FLOW, *THERMAL RADIATION), (*AERODYNAMICS, *ACOUSTICS), WAVE PROPAGATION, INTERACTIONS, MATHEMATICAL MODELS, APPROXIMATION(MATHEMATICS), PARTIAL DIFFERENTIAL EQUATIONS, ONE DIMENSIONAL FLOW, PULSES

Subject Categories : Acoustics
      Fluid Mechanics
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE