Speaker
Description
Diffusiophoresis refers to the out-of-equilibrium phenomenon that triggers colloid migration along gradients of local salt concentration in its ambient. First discovered in the 1950s [1], later developed theoretically in the 1980s [2], this phenomenon has recently caught the attention of scientists across disciplines. Due to the logarithmic dependence of the diffusiophoretic drift velocity on the salt gradients, small variations in salt concentrations can lead to unexpectedly large colloid migration. It has been well-established that diffusiophoresis is promising in colloid manipulation strategies. However, the understanding of this phenomenon in the context of porous media is limited. Recent investigations have demonstrated that spatial heterogeneities in the medium that support salt gradients for relatively larger times are conducive to diffusiophoresis [3,4]. On a slightly different note, in synthetically generated 3D unsaturated geometries characterized by low-flow dead-end regions and high-flow well-connected transmitting regions, it was suggested that mixing, and subsequently, reactivity are suppressed compared to their 2D counterparts [5]. Naturally, these observations implore the next question: How does diffusiophoresis transpire in realistic 3D geometries where salt gradients are likely to persist at different scales? Furthermore, from an application point of view, addressing this question will provide crucial insights towards the optimal exploitation of diffusiophoresis in technologies such as groundwater contamination and remediation. To this end, we use high performance computing and pore-scale simulations to investigate diffusiophoresis in 3D heterogeneous solute landscapes. Optimal conditions for enhanced diffusiophoresis will be identified for achieving systematic colloid removal or retention, as desired, by tuning the control parameters. The relevance of diffusiophoresis in realistic 3D media and the underlying pore-scale governing mechanisms will be elucidated. These results constitute some of the few pioneering works and are expected to pave the way towards attaining controlled colloid manipulation through porous media.
| References | [1] Derjaguin et al. (1947), “Kinetic phenomenon in boundary films of liquids”, Colloid J. USSR, 9, 335-347. [2] Anderson (1989), “Colloid transport by interfacial forces”, Annu. Rev. Fluid Mech., 21 (1), 61-99. [3] Jotkar et al. (2024), “The impact of diffusiophoresis on hydrodynamic dispersion and filtration in porous media”, J. Fluid Mech. (2024), vol. 991, A8, doi:10.1017/jfm.2024.546 [4] Jotkar et al. (2024), “Diffusiophoresis of colloids in partially-saturated porous media”, Advances in Water Resources, vol. 193 (2024) 104828, doi.org/10.1016/j.advwatres.2024.104828 [5] Farhat et al. (under review in Geophysical Review Letters), “Non-Monotonic Dependence of Mixing on Phase Saturation in 3D Porous Media”, doi:10.22541/essoar.175624238.89280481/v1 |
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| Country | Spain |
| Green Housing & Porous Media Focused Abstracts | This abstract is related to Green Housing |
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