Effective transient behaviour of inclusions in diffusion problems

Laurence Brassart, Laurent Stainier

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Abstract

This paper is concerned with the effective transport properties of heterogeneous media in which there is a high contrast between the phase diffusivities. In this case the transient response of the slow phase induces a memory effect at the macroscopic scale, which needs to be included in a macroscopic continuum description. This paper focuses on the slow phase, which we take as a dispersion of inclusions of arbitrary shape. We revisit the linear diffusion problem in such inclusions in order to identify the structure of the effective (average) inclusion response to a chemical load applied on the inclusion boundary. We identify a chemical creep function (similar to the creep function of viscoelasticity), from which we construct estimates with a reduced number of relaxation modes. The proposed estimates admit an equivalent representation based on a finite number of internal variables. These estimates allow us to predict the average inclusion response under arbitrary time-varying boundary conditions at very low computational cost. A heuristic generalisation to concentration-dependent diffusion coefficient is also presented. The proposed estimates for the effective transient response of an inclusion can serve as a building block for the formulation of multi-inclusion homogenisation schemes.

Original languageEnglish
Pages (from-to)981-998
Number of pages18
JournalZamm-Zeitschrift Fur Angewandte Mathematik Und Mechanik
Volume98
Issue number6
DOIs
Publication statusPublished - 1 Jun 2018

Keywords

  • 04A25
  • Heat transfer
  • heterogeneous media
  • homogenisation
  • mass tranfer
  • memory effect
  • viscoelasticity

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