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Homogenization of compressible fluid flow in porous media with interfacial flow barrier

100%

Royer P. , Auriault J.

Archives of Mechanics

1999

tom Vol. 51, nr 3-4

469-486

This work is concerned with modelling compressible fluid flow in a composite porous medium with interfacial flow barrier. The macroscopic behaviour and the effective permeability are obtained by homogenization, i.e. by upscaling the description at the heterogeneity scale. Five distinct macroscopic models are derived that relate to five relative orders of magnitude of the interfacial conductance with respect to the permeabilities of the constituents.

On non-Fickian hyperbolic diffusion

80%

Auriault J. L. , Lewandowska J. , Royer P.

2008

tom Vol. 30, nr 1-2

139-146

Fick's law expresses the proportionality of solute flux with respect to concentration gradient. Similar relations are given by Darcy's law for the fluid flow in porous media, Ohm's law for the electric flux and Fourier's law for heat transfers. When introduced in the corresponding balance equations, these flux laws yield diffusion equations of parabolic character. Different attempts have been made to obtain hyperbolic equations so as to point out propagative phenomena. This was done by adding a time derivative flux term to the flow law. In this paper, we focus on solute transport. Two possible non-Fickian diffusion cases are addressed. We firstly investigate diffusion in fluids by a mechanistic approach. Secondly, we study the macroscopic diffusion law in composite materials with large contrast of diffusion coefficient. We show that the diffusion law obtained yields hyperbolicity for drastically short characteristic times or non-propagative waves.