# Computation of Saturation Dependence of Effective Diffusion Coefﬁcient in Unsaturated Argillite Micro-fracture by Lattice Boltzmann Method

* Corresponding author
Abstract : Getting access to the effective diffusion coefﬁcient is a key point to provide realistic predictions of migration of radionuclides from radioactive waste repository in deep argillaceous geological formations. In the present work, the effective diffusion coefﬁcient was computed inside an argillite micro-fracture as a function of its saturation level. The micrometric fracture geometry was extracted from the X-ray $\mu$-tomography image (0.7$\mu m$ voxel resolution) of an Opalinus clay sample. It was collected in the host rock excavated damaged zone surrounding a borehole in the Mont Terri laboratory. The computations were performed using two two-relaxation-time lattice Boltzmann models. The ﬁrst one, a phase separation model,was used to extract the connected liquid phase Inside the fracture for given saturations. The second, a diffusion model, was used to compute non-reactive tracer diffusion in the connected liquid phase of the fracture and to calculate the effective diffusion coefﬁcient for the associated saturations. The dependence of the effective diffusion coefﬁcient on saturation was found to be quasi-linear and to qualitatively match the Maxwell expression for saturations lower than 0.8.
Keywords :
Document type :
Journal articles
Complete list of metadata

https://hal-cea.archives-ouvertes.fr/cea-02421902
Contributor : amplexor amplexor Connect in order to contact the contributor
Submitted on : Tuesday, January 5, 2021 - 9:00:14 PM
Last modification on : Wednesday, January 6, 2021 - 10:39:21 AM
Long-term archiving on: : Wednesday, April 7, 2021 - 9:34:01 AM

### File

0000167032_001.PDF
Files produced by the author(s)

### Citation

A. Genty, S. Gueddani, M. Dymitrowska. Computation of Saturation Dependence of Effective Diffusion Coefﬁcient in Unsaturated Argillite Micro-fracture by Lattice Boltzmann Method. Transport in Porous Media, Springer Verlag, 2017, 117, pp.149-168. ⟨10.1007/s11242-017-0826-z⟩. ⟨cea-02421902⟩

Record views