Temperature gradient effects on sound wave propagation

Sound wave propagation through regions of non-uniform temperature distribution in a gas is studied numerically. The main objective of this study is to determine the impact of temperature gradients on the sound wave parameters and to evaluate the effectiveness of using glow discharge plasma in an ambient environment as a sound barrier. Sound attenuation through the hot gas region is studied systematically for a range of sound wave and thermal field parameters. Particular attention is given to the case of a sound wavelength comparable to the thickness of the thermal barrier. In this report we consider the two-dimensional case where the compressible unsteady Euler's equations together with the ideal gas state equation are solved using a finite volume scheme. Global sound energy attenuation is shown to depend on the thickness of the thermal barrier as well as the temperature ratio between the two zones, while local attenuation is additionally dependent upon the location of the interrogation point.