Background. As part of a new collaboration between the university of Rennes (France) and the IDAEA-CSIC Barcelona (Spain), we are opening a postdoc position on the study of reactive transport processes in multiphase porous media flows. This position is jointly funded by the ERC project Uplift (reference 101115760, funded by the European Union), on upscaling reactive transport in partially saturated porous media and the ANR project Inflow, on fluid-solid reactions in unsaturated porous media. Relevant backgrounds include numerical modelling, transport in porous media, and fluid mechanics.

Scientific project. The unsaturated soil zone, also termed the vadose zone, is of great importance in providing the biosphere with water and nutrients[1]. Hydrologically, it is the main component controlling water flow from the land surface to aquifers[2]. Chemically, it is often regarded as a filter that removes toxic compounds. Hence, fluid flow and chemical reactions in this unsaturated zone control the input of contaminants into groundwater reservoirs, which represent a substantial portion of the Earth’s freshwater supply[3]. A key property of soils is that, in addition to being structurally heterogeneous, they are generally characterized by a heterogeneous proportion of water and air, which induces complex liquid flow paths and contaminant dispersion processes. Recent advances have shown that this leads to transport dynamics that fundamentally differ from those known in saturated porous media[4],[5],[6], including highly heterogeneous velocity fields, fluctuating flow paths, persistent incomplete mixing and broad solute travel time distributions. A key challenge is to understand and model the impact of these transport dynamics on reactive processes. 

We will address this question by developing pore scale numerical models, resolving the distribution of water and air within pores, as well as flow, transport and reaction processes. We will then use recent random walk theories[7],[8],[9] to upscale the corresponding reactive transport processes and establish effective reaction kinetics describing the impact of unsaturated flow dynamics on solid-fluid reactions.  

Conditions. The successful candidate will be hired for two years, possibly extendable, and will be hosted in Rennes (France) for the first year and in Barcelona (Spain) for the second year. Both groups include a large team of PhD students, postdocs, researchers and professors working on porous media processes. She/he will receive a postdoctoral salary in keeping with standard contracts offered in France and Spain.

How to apply?  Please contact Tanguy Le Borgne (tanguy.le-borgne@univ-rennes.fr) and Tomás Aquino (tomas.aquino@idaea.csic.es)
 

[1] Šimůnek, J., Jarvis, NJ., van Genuchten M. Th., Gärdenäs A. J. of Hydrol. 2003, 272, 14–35.

[2] Šimůnek, J., van Genuchten M. Th., Šejna M. Vadose Zone J. 2008, 7, 587–600.

[3] Druhan J., Tournassat C. Reactive Transport in Natural and Engineered Systems. Rev, Mineral. Geochem. 2019, 85, 500.

[4] Jiménez‐Martínez, J., Anna, P. D., Tabuteau, H., Turuban, R., Borgne, T. L., & Méheust, Y. (2015). Geophysical Research Letters, 42(13), 5316-5324.

[5] Jiménez‐Martínez, J., Le Borgne, T., Tabuteau, H., & Méheust, Y. (2017). Water Resources Research, 53(2), 1457-1472.

[6] Velásquez‐Parra, A., Aquino, T., Willmann, M., Méheust, Y., Le Borgne, T., & Jiménez‐Martínez, J. (2022). Geophysical Research Letters, 49(3).

[7] Aquino, T. & Le Borgne, T. (2021). Journal of Fluid Mechanics, 910, A12.

[8] Aquino, T. & Le Borgne, T. (2021). Advances in Water Resources, 154, 103981.

[9] Aquino, T., Le Borgne, T., & Heyman, J. (2023). Physical Review Letters, 130(26), 264001.