Modeling diffusion processes in the presence of a diffuse layer at charged mineral surfaces: a benchmark exercise.
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| Title: | Modeling diffusion processes in the presence of a diffuse layer at charged mineral surfaces: a benchmark exercise. |
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| Authors: | Tournassat, Christophe1,2,3 (AUTHOR) c.tournassat@brgm.fr, Steefel, Carl I.1 (AUTHOR) |
| Source: | Computational Geosciences. Aug2021, Vol. 25 Issue 4, p1319-1336. 18p. |
| Subjects: | Diffusion processes, Nernst-Planck equation, Radioactive waste disposal, Electric potential, Finite differences, Isometric exercise, Radioactive wastes |
| Abstract: | The electrostatic properties of clay mineral surfaces play a significant role in their diffusion properties. The negative electrostatic potential field at clay mineral surfaces results in the presence of a diffuse layer that balances the mineral surface charge. The diffusion properties of the porosity fraction that is affected by this phenomenon are different from the diffusion properties of electroneutral bulk water. These properties have attracted growing interest from diverse communities in the past years, especially in the field of study of radioactive waste disposal. The influence of the diffuse layer can be described at the continuum scale by a set of equations that are formulated in terms of the Nernst-Planck equation. The number of codes that can handle the coupling between transport properties in clay affected by the presence of a diffuse layer in the porosity and chemical reactions is very limited, and no benchmark exercises have been published yet that make it possible to validate the numerical implementation of these equations in reactive transport codes. The present study proposes a set of benchmark exercises of increasing complexity that highlight caveats related to the finite difference (volume) treatment of the Nernst-Planck equation in the presence of a diffuse layer in heterogeneous systems. Once these problems are identified and solved, the codes PHREEQC, CrunchClay, and a new Fortran routine written for this study gave results in very good agreement for most of the benchmark exercises. When present, the differences in results were directly traceable to the differences in averaging methods at grid cell boundaries, and to the consideration or the omission of the activity gradient term in the Nernst-Planck equation. [ABSTRACT FROM AUTHOR] |
| Copyright of Computational Geosciences is the property of Springer Nature and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Links: – Type: pdflink Text: Availability: 0 |
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| Header | DbId: egs DbLabel: Engineering Source An: 151541780 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Modeling diffusion processes in the presence of a diffuse layer at charged mineral surfaces: a benchmark exercise. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Tournassat%2C+Christophe%22">Tournassat, Christophe</searchLink><relatesTo>1,2,3</relatesTo> (AUTHOR)<i> c.tournassat@brgm.fr</i><br /><searchLink fieldCode="AR" term="%22Steefel%2C+Carl+I%2E%22">Steefel, Carl I.</searchLink><relatesTo>1</relatesTo> (AUTHOR) – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Computational+Geosciences%22">Computational Geosciences</searchLink>. Aug2021, Vol. 25 Issue 4, p1319-1336. 18p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Diffusion+processes%22">Diffusion processes</searchLink><br /><searchLink fieldCode="DE" term="%22Nernst-Planck+equation%22">Nernst-Planck equation</searchLink><br /><searchLink fieldCode="DE" term="%22Radioactive+waste+disposal%22">Radioactive waste disposal</searchLink><br /><searchLink fieldCode="DE" term="%22Electric+potential%22">Electric potential</searchLink><br /><searchLink fieldCode="DE" term="%22Finite+differences%22">Finite differences</searchLink><br /><searchLink fieldCode="DE" term="%22Isometric+exercise%22">Isometric exercise</searchLink><br /><searchLink fieldCode="DE" term="%22Radioactive+wastes%22">Radioactive wastes</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: The electrostatic properties of clay mineral surfaces play a significant role in their diffusion properties. The negative electrostatic potential field at clay mineral surfaces results in the presence of a diffuse layer that balances the mineral surface charge. The diffusion properties of the porosity fraction that is affected by this phenomenon are different from the diffusion properties of electroneutral bulk water. These properties have attracted growing interest from diverse communities in the past years, especially in the field of study of radioactive waste disposal. The influence of the diffuse layer can be described at the continuum scale by a set of equations that are formulated in terms of the Nernst-Planck equation. The number of codes that can handle the coupling between transport properties in clay affected by the presence of a diffuse layer in the porosity and chemical reactions is very limited, and no benchmark exercises have been published yet that make it possible to validate the numerical implementation of these equations in reactive transport codes. The present study proposes a set of benchmark exercises of increasing complexity that highlight caveats related to the finite difference (volume) treatment of the Nernst-Planck equation in the presence of a diffuse layer in heterogeneous systems. Once these problems are identified and solved, the codes PHREEQC, CrunchClay, and a new Fortran routine written for this study gave results in very good agreement for most of the benchmark exercises. When present, the differences in results were directly traceable to the differences in averaging methods at grid cell boundaries, and to the consideration or the omission of the activity gradient term in the Nernst-Planck equation. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Computational Geosciences is the property of Springer Nature and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1007/s10596-019-09845-4 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 18 StartPage: 1319 Subjects: – SubjectFull: Diffusion processes Type: general – SubjectFull: Nernst-Planck equation Type: general – SubjectFull: Radioactive waste disposal Type: general – SubjectFull: Electric potential Type: general – SubjectFull: Finite differences Type: general – SubjectFull: Isometric exercise Type: general – SubjectFull: Radioactive wastes Type: general Titles: – TitleFull: Modeling diffusion processes in the presence of a diffuse layer at charged mineral surfaces: a benchmark exercise. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Tournassat, Christophe – PersonEntity: Name: NameFull: Steefel, Carl I. IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 08 Text: Aug2021 Type: published Y: 2021 Identifiers: – Type: issn-print Value: 14200597 Numbering: – Type: volume Value: 25 – Type: issue Value: 4 Titles: – TitleFull: Computational Geosciences Type: main |
| ResultId | 1 |
