Sound propagation in thin-walled elastic pipe with viscous liquid-bubble mixture and deformable central rod

Sound propagation in coaxial waveguide with bubbly liquid is investigated. It is assumed that the central part of the pipe is occupied by circular elastic rod, the tube wall can be treated as a thin elastic shell, and the liquid is pure viscous. Volume concentration of free gas is supposed to be small. The goal of the study is to estimate theoretically acoustic properties of such waveguide for different gas concentrations, bubble sizes, liquid viscosities and gap width. Results of analysis illustrate strong influence of liquid, gas, elastic shell and rod parameters on sound dispersion and attenuation.