Investigation of ultrasonic propagation in high attenuation porous materials

This research examines ultrasonic wave propagation in air-saturated plastic foams used for noise pollution reduction, questioning the effectiveness of current models such as the well known Johnson-Champoux-Allard model at high frequencies. These foams present a challenge for existing models to accurately depict visco-inertial and thermal interactions within their pores. The study highlights the model's failure to align experimental results with theoretical predictions. It introduces novel parameters denoted as Σ and V for viscous effects, and Σ′ and V ′ for thermal effects, to improve the representation of fluid-sturcture interactions. These parameters suggest a more significant boundary layer effect within the pores than previously considered. This approach aims to provide additional physical context for the principles governing the behavior of highly attenuating porous media and to explore new avenues for material characterization that surpass the limitations of existing models.