From Knudsen diffusion to Levy walks
Centre de Recherche sur la Matiére Divisée
CNRS, 1b rue de la Ferollerie 45071 Orleans Cedex 02, France
Corresponding author: firstname.lastname@example.org
Accepted: 14 August 1997
In this letter, we show that 3D Knudsen diffusion inside disordered porous media can be analysed in terms of a continuous time random walk formalism (CTRW) recently proposed for 1D intermittent chaotic systems. This approach mainly involves the pore chord distribution function . Differently no Gaussian regimes are observed when follows an algebraic law with an exponent . For , Knudsen diffusion is a Levy walk. This Levy walk is dominated by ballistic dynamics for (mass or surface fractal) and becomes hyperdiffusive for . For , we reach the marginal case separating the Levy and the Gaussian statistics. In this regime, we discuss some properties of the slit pore geometry which can be compared with a Sinai's billiard without horizon.
PACS: 05.40.+j – Fluctuation phenomena, random processes, and Brownian motion / 47.55.Mh – Flows through porous media / 51.10.+y – Kinetic and transport theory of gases
© EDP Sciences, 1997