Beschreibung:
<jats:p>A research program has been initiated in 2002 in order to link microstructure of high porosity open-cell foams to their acoustic properties. This paper is intended to highlight the main results of this study. The general objective of the research program is the determination of the acoustical macro-behavior from the physics at the local scale. A real rigid-framed porous media is studied. To this end, one needs first to determine the local geometry of the media, and second to solve over this geometry the partial differential equations that govern dissipation phenomena by thermal and viscous effects. The first step has been overcome by the technique of computed microtomography. This leads to experimental identification of the parameters of an idealized periodic unit-cell. The second step, solving harmonic heat and viscous fluid equations, is performed using Brownian motion and finite element simulations, respectively. Then, macroscopic behavior is obtained by spatial averaging of the local and frequency-dependent thermal and velocity fields. Results are presented in terms of two dynamic characteristic functions (viscous and thermal permeabilities) compared to impedance tube measurements. This computational methodology may be seen as a first step to optimize the microstructure of foams from a bottom-up approach for better sound proofing.</jats:p>