Schematic representation of the growing complexity of motionless skeleton models regarding the microstructure of the porous materials.

The tables reported below present, for a large number of models, the parameters they require to describe the visco-thermal dissipation effects when sound waves propagate through a porous medium.

Delany-Bazley model

This empirical model based on measurements results for fibrous materials should not be used without corrections proposed by Miki (see Delany-Bazley-Miki model below).

Parameter(s) Usual notation
Static air flow resistivity $\sigma$

Delany-Bazley-Miki model

This empirical model may be used to described fibrous material behaviors.

Parameter(s) Usual notation
Static air flow resistivity $\sigma$

Miki model

The year he published his corrections of Delany-Bazley expressions (1990), Miki also presented a 3-parameter model.

Parameter(s)Usual notation
Static air flow resistivity $\sigma$
Open porosity $\phi$
High frequency limit of the tortuosity $\alpha_{\infty}$

Johnson-Champoux-Allard

This semi-phenomenological model may be used to described the dissipation behavior of fibrous materials or materials with arbitrary pore shapes without important pore section variations.

Parameter(s)Usual notation
Static air flow resistivity $\sigma$
Open porosity $\phi$
High frequency limit of the tortuosity $\alpha_{\infty}$
Viscous characteristic length $\Lambda$
Thermal characteristic length $\Lambda'$

Johnson-Champoux-Allard-Lafarge

This semi-phenomenological model may be used to described the dissipation behavior of materials with arbitrary pore shapes without important pore section variations.

Parameter(s)Usual notation
Static air flow resistivity $\sigma$
Open porosity $\phi$
High frequency limit of the tortuosity $\alpha_{\infty}$
Viscous characteristic length $\Lambda$
Thermal characteristic length $\Lambda'$
Static thermal permeability $k'_{0}$

Johnson-Champoux-Allard-Pride-Lafarge

This semi-phenomenological model may be used to described the dissipation behavior of materials with arbitrary pore shapes and important pore section variations.

Parameter(s)Usual notation
Static air flow resistivity $\sigma$
Open porosity $\phi$
High frequency limit of the tortuosity $\alpha_{\infty}$
Viscous characteristic length $\Lambda$
Thermal characteristic length $\Lambda'$
Static thermal permeability $k'_{0}$
Static viscous tortuosity $\alpha_0$
Static thermal tortuosity $\alpha_0'$

Wilson model

This semi-phenomenological model may be used to described the dissipation behavior of fibrous materials or materials with arbitrary pore shapes without important pore section variations.

Parameter(s)Usual notation
High frequency limit of the dynamic density $\rho_{\infty}$
Vorticity-mode relaxation time $\tau_{\textrm{vor}}$
High frequency limit of the bulk modulus $K_{\infty}$
Entropy-mode relaxation time $\tau_{\textrm{ent}}$