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A Simple Model for Anomalous Relaxation in Porous Media

Published online by Cambridge University Press:  10 February 2011

Mariela Araujo
Affiliation:
INTEVEP S.A, Apartado 76343. Caracas 1070-A Venezuela.
Orlando Gonzalez
Affiliation:
Departamento de Física, Universidad Central de Venezuela. Caracas, Venezuela.
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Abstract

We present a simple model to explain anomalous relaxation in random porous media. The model, based on the properties of random walks on a disordered structure, is able to describe essential features of the relaxation process in terms of a one body picture, in which the many body effects are approximated by geometrical restrictions on the particles diffusion. Disorder is considered as a random variable (quenched and annealed) taken from a power-law distribution |μ|ξμ−1. Quantities relevant to relaxation phenomena, such as the characteristic function and the particle density are calculated. Different regimes are observed as a function of the disorder parameter μ. For μ > 1 the relaxation is of exponential or Debye type, and turns into a stretched exponential as μ decreases. We compare numerical predictions (based on Monte Carlo simulations) with experimental data from porous rocks obtained by Nuclear Magnetic Resonance, and numerical data from other disordered systems.

Type
Research Article
Copyright
Copyright © Materials Research Society 1996

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References

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