Sound propagation in a real fluid subject to diffusion

The effects of viscosity, heat conductivity and diffusion on one-dimensional sound waves have been analyzed. The governing equations in the acoustic approximation have been reduced to a wave equation consisting of different order wave operators. The normal mode analysis of this equation has established an increased attenuation of the waves due to the diffusion effect. Furthermore, the operator equation has been subjected to a qualitative analysis, and detailed comments have been made in regard to the stability of motion and the roles played by higher and lower order waves.