https://doi.org/10.1140/epje/s10189-026-00566-y
Research - Flowing Matter
Free-interface convective mixing in porous media: 2D and 3D numerical simulations
1
E2S UPPA, CNRS, LFCR, Universite de Pau et des Pays de l’Adour, 64600, Anglet, France
2
Dipartimento di Fisica and INFN, Università degli Studi di Torino, via P. Giuria 1, 10125, Torino, Italy
a
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Received:
16
September
2025
Accepted:
4
February
2026
Published online:
2
March
2026
Abstract
We investigate convective mixing in porous media in the presence of a free interface separating two miscible fluids initially arranged in a stable configuration. This problem is motivated by the dynamics of supercritical 
overlying a brine-saturated porous medium, as well as analogous laboratory experiments. Diffusion of the lighter upper layer into the denser lower layer results in a layer with a density greater than that of the denser lower layer, which then induces an unstable stratification that triggers convection. Using high-resolution direct numerical simulations, we analyse the system dynamics in both two- and three-dimensional geometries and for different diffusivities. Our results show that in 2D the process is faster, with dissolution fluxes about 
higher than in 3D. Convective plumes deform the initially flat interface, creating an iso-concentration surface whose vertical extent increases over time. These findings highlight the need for caution when extrapolating two-dimensional results to three-dimensional applications.
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© The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature 2026
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
