Fractal Model for Acoustic Absorbing of Porous Fibrous Metal Materials

Efficient finite element approach for structural-acoustic applications including 3D modelling of sound absorbing porous materials

This thesis presents efficient finite element solutions of poro-elasto-acoustic coupled problems using modal-based approaches adapted to non conservative problems, combined with an interpolation method in frequency, based on Padé approximants. The performance of the proposed methods and their combination is demonstrated on several 1D to 3D coupled problems. Conclusions are drawn to provide indi...

Multiple scattering of acoustic waves and porous absorbing media.

Porous media like air-saturated polymer foams with open cells, have a nontrivial frequency-dependent absorption that arises due to viscous and thermal effects at the scale of the rigid frame microstructure. In order to produce multiple scattering at ultrasonic frequencies, mesoscale scatterers are introduced in the porous medium host. The effective wave number of such a multiscale medium should...

Measuring static viscous permeability of porous absorbing materials.

Conventional acoustical methods for measuring the permeability or flow resistivity of a porous material require a priori estimation of the porosity. In this work, an acoustical method is presented in which a simplified expression (independent of both the frequency and porosity) for the transmitted waves at the Darcy's regime (low frequency range) is derived, and used for the inverse determinati...

Airflow resistivity of models of fibrous acoustic materials

Fractal Derivative Model for Air Permeability in Hierarchic Porous Media

and Applied Analysis 3 where k is a constant, α is the fractal dimension, L0 is the smallest measure, and u t is the distance between two points in the porous media. The distance between two points in a discontinuous space is