Ultrasonic characterisation of poroux materials
Résumé
Acoustic models of the acoustics of porous and perforated media involve a set of physical parameters. Some of the parameters, the tortusity, the viscous and thermal characteristic lengths are defined for a perfect incompressible and inviscid fluid saturating the porous medium. It is shown that ultrasonic propagation in air-saturated materials can be used to determine these parameters. A basic method involving air-coupled ultrasonic transducers is presented. Variants of this method and a practical implementation of one of these is proposed.