Bothe, Dieter ; Druet, Pierre-Étienne (2023)
On the structure of continuum thermodynamical diffusion fluxes— A novel closure scheme and its relation to the Maxwell–Stefan and the Fick–Onsager approach.
In: International Journal of Engineering Science, 184
doi: 10.1016/j.ijengsci.2023.103818
Artikel, Bibliographie
Kurzbeschreibung (Abstract)
This paper revisits the modeling of multicomponent diffusion within the framework of thermodynamics of irreversible processes. We briefly review the two well-known main approaches, leading to the generalized Fick–Onsager multicomponent diffusion fluxes or to the generalized Maxwell–Stefan equations. The latter approach has the advantage that the resulting fluxes are consistent with non-negativity of the partial mass densities for non-singular and non-degenerate Maxwell–Stefan diffusivities. On the other hand, this approach requires computationally expensive matrix inversions since the fluxes are only implicitly given. We propose and discuss a novel and more direct closure which avoids the inversion of the Maxwell–Stefan equations. It is shown that all three closures are actually equivalent under the natural requirement of positivity for the concentrations, thus revealing the general structure of continuum thermodynamical diffusion fluxes. As a special case, the new closure also gives rise to a core-diagonal diffusion model in which only those cross-effects are present that are necessary to guarantee consistency with total mass conservation, plus a compositional dependence of the diffusivity. This core-diagonal closure turns out to provide a rigorous fundament for recent extensions of the Darken equation from binary mixtures to the general multicomponent case. As an outcome of our investigation, we also address different questions related to the sign of multicomponent thermodynamic or Fickian diffusion coefficients. We show rigorously that, in general, the second law requires positivity properties for tensors and operators rather than for scalar diffusivities.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2023 |
| Autor(en): | Bothe, Dieter ; Druet, Pierre-Étienne |
| Art des Eintrags: | Bibliographie |
| Titel: | On the structure of continuum thermodynamical diffusion fluxes— A novel closure scheme and its relation to the Maxwell–Stefan and the Fick–Onsager approach |
| Sprache: | Englisch |
| Publikationsjahr: | 2023 |
| Ort: | Amsterdam |
| Verlag: | Elsevier |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | International Journal of Engineering Science |
| Jahrgang/Volume einer Zeitschrift: | 184 |
| DOI: | 10.1016/j.ijengsci.2023.103818 |
| URL / URN: | https://www.sciencedirect.com/science/article/abs/pii/S00207... |
| Kurzbeschreibung (Abstract): | This paper revisits the modeling of multicomponent diffusion within the framework of thermodynamics of irreversible processes. We briefly review the two well-known main approaches, leading to the generalized Fick–Onsager multicomponent diffusion fluxes or to the generalized Maxwell–Stefan equations. The latter approach has the advantage that the resulting fluxes are consistent with non-negativity of the partial mass densities for non-singular and non-degenerate Maxwell–Stefan diffusivities. On the other hand, this approach requires computationally expensive matrix inversions since the fluxes are only implicitly given. We propose and discuss a novel and more direct closure which avoids the inversion of the Maxwell–Stefan equations. It is shown that all three closures are actually equivalent under the natural requirement of positivity for the concentrations, thus revealing the general structure of continuum thermodynamical diffusion fluxes. As a special case, the new closure also gives rise to a core-diagonal diffusion model in which only those cross-effects are present that are necessary to guarantee consistency with total mass conservation, plus a compositional dependence of the diffusivity. This core-diagonal closure turns out to provide a rigorous fundament for recent extensions of the Darken equation from binary mixtures to the general multicomponent case. As an outcome of our investigation, we also address different questions related to the sign of multicomponent thermodynamic or Fickian diffusion coefficients. We show rigorously that, in general, the second law requires positivity properties for tensors and operators rather than for scalar diffusivities. |
| Fachbereich(e)/-gebiet(e): | DFG-Sonderforschungsbereiche (inkl. Transregio) DFG-Sonderforschungsbereiche (inkl. Transregio) > Sonderforschungsbereiche DFG-Sonderforschungsbereiche (inkl. Transregio) > Sonderforschungsbereiche > SFB 1194: Wechselseitige Beeinflussung von Transport- und Benetzungsvorgängen DFG-Sonderforschungsbereiche (inkl. Transregio) > Sonderforschungsbereiche > SFB 1194: Wechselseitige Beeinflussung von Transport- und Benetzungsvorgängen > Projektbereich B: Modellierung und Simulation DFG-Sonderforschungsbereiche (inkl. Transregio) > Sonderforschungsbereiche > SFB 1194: Wechselseitige Beeinflussung von Transport- und Benetzungsvorgängen > Projektbereich B: Modellierung und Simulation > B01: Modellierung und VOF-basierte Simulation der Multiphysik irreversibler thermodynamischer Transferprozesse an dynamischen Kontaktlinien 04 Fachbereich Mathematik 04 Fachbereich Mathematik > Analysis 04 Fachbereich Mathematik > Analysis > Mathematische Modellierung und Analysis |
| Hinterlegungsdatum: | 07 Dez 2023 13:58 |
| Letzte Änderung: | 07 Dez 2023 13:58 |
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