Multiphysics Modelling of Sound Absorption in Rigid Porous Media Based on Periodic Representations of Their Microstructural Geometry

T.G. Zielinski[1]
[1]Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw, Poland
Veröffentlicht in 2013

Sound absorption in porous materials with rigid frame and open porosity can be very effectively estimated by applying the Johnson-Allard model in order to substitute a porous medium with an equivalent effective fluid and then utilise the Helmholtz equation for time-harmonic acoustics. The model uses several parameters which characterize the micro-geometry of porous material from the macroscopic perspective; they are: the total porosity, the viscous permeability and its thermal analogue, the tortuosity, and two characteristic lengths -- one specific for viscous forces, the other for thermal effects. The acoustic absorption for a layer of freely packed assemblies of small rigid spheres was measured and compared with the result calculated from the microsctructural analyses using COMSOL Multiphysics®.