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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Transport in porous media 21 (1995), S. 47-70 
    ISSN: 1573-1634
    Keywords: ‘Long-tail’ effect ; pollutant ; diffusion ; double porosity ; homogenization ; modelization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract In the paper anomalous diffusion appearing in a porous medium composed of two porous components of considerably different diffusion characteristics is examined. The differences in diffusivities are supposed to result either from two medium types being present or from variations in pore size (double porosity media). The ‘long-tail’ effect is predicted using the homogenization approach based on the application of multiple scale asymptotic developments. It is shown that, if the ratio of effective diffusion coefficients of two porous media is of the order of magnitude smaller or equal O(ε 2), whereε is a homogenization parameter, then the macroscopic behaviour of the composite may be affected by the presence of ‘tail-effect’. The results of the theoretical analysis were applied to a problem of diffusion in a bilaminate composite. Analytical calculations were performed to show the presence of the ‘long-tail’ effect in two particular cases.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Transport in porous media 16 (1994), S. 31-52 
    ISSN: 1573-1634
    Keywords: coupled flows ; homogenization ; Onsager relations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract In this paper, the derivation of macroscopic transport equations for this cases of simultaneous heat and water, chemical and water or electrical and water fluxes in porous media is presented. Based on themicro-macro passage using the method of homogenization of periodic structures, it is shown that the resulting macroscopic equations reveal zero-valued cross-coupling effects for the case of heat and water transport as well as chemical and water transport. In the case of electrical and water transport, a nonsymmetrical coupling was found.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Transport in porous media 17 (1994), S. 33-57 
    ISSN: 1573-1634
    Keywords: double porosity ; fractured porous media ; gas filtration ; homogenization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract The highly compressible fluid flow through a three-scales rigid porous medium (pore, fracture, macroscopic sample) is investigated using a homogenization method. The macroscopic description is strongly dependent on the separation of the different scales, and three cases are considered. The pores either play the role of a compressible fluid reservoir, introduce a memory effect, or are ignored, respectively. The homogenization result is compared to classical phenomenological models that are available in the case of slightly compressible fluids. Pseudo-steady state models are shown to give a rough description of the phenomenon.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Mechanics of Cohesive-frictional Materials 2 (1997), S. 205-221 
    ISSN: 1082-5010
    Keywords: pollutant diffusion ; advection ; porous media ; surface transfer resistance ; physical modelling ; homogenization ; model classification ; Engineering ; Civil and Mechanical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In the paper, an attempt to model local equilibrium and local non-equilibrium in pollutant migration in porous media is presented. Diffusion is assumed to occur in the pores as well as in the solid porous matrix. The macroscopic models are developed using the homogenization method (asymptotic expansion technique). The resulting macroscopic equations show either a one-concentration field or two-concentration fields or memory effects. The domains of validity of all the presented models are also determined. Local cell problems are provided to compute the effective diffusion tensors. The conditions for the local mass equilibrium assumption to be valid are derived in terms of the dimensionless characteristic parameters. The effect of pollutant source distributions is also investigated. © 1997 John Wiley & Son, Ltd.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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