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Spectral induced polarization (SIP) has the potential for monitoring reactive processes in the subsurface. While strong SIP responses have been measured in response to calcite precipitation, their origin and mechanism remain debated. Here we present a novel geo-electrical millifluidic setup designed to observe microscale reactive transport processes while performing SIP measurements. We induced calcite precipitation by injecting two reactive solutions into a porous medium, which led to highly localized precipitates at the mixing interface. Strikingly, the amplitude of the SIP response increased by 340% during the last 7% increase in precipitate volume. Furthermore, while the peak frequency in SIP response varied spatially over 1 order of magnitude, the crystal size range was similar along the front, contradicting assumptions in the classical grain polarization model. We argue that the SIP response of calcite precipitation in such mixing fronts is governed by Maxwell–Wagner polarization due to the establishment of a precipitate wall. Numerical simulations of the electric field suggested that spatial variation in peak frequency was related to the macroscopic shape of the front. These findings provide new insights into the SIP response of calcite precipitation and highlight the potential of geoelectrical millifluidics for understanding and modeling electrical signatures of reactive transport processes.

Abrasive water-jet manufacturing process can shape a lot of materials ranging from metals to glasses. It has a lot of advantages, as its low cutting forces, but remains quite difficult to control. Indeed, the process is leaded by the abrasive particle trajectories which depends on the water static pressure and many other parameters. The impact pressure on the work-piece is commonly modeled by a two Gaussian fit sum which are representative of the particles velocity distribution and the granulometry respectively. Today no studies based on discrete elements take into account the mixing chamber and the focal canon which are the two main steps of the abrasive water-jet tool constitution. In this preliminary work we propose to model the flow through the focal canon until the target impact by an original numeric granular approach. The Non-Smooth Contact Dynamics is an efficient method on a large range of simulation domains. In our case, we consider the water phase and the abrasive phase as two collections of distinct polydisperse elements. The masses are corrected and the contact interaction laws are adjusted to account for an equivalent fluid which similar mechanical properties. These two phases are mixed in a chamber and focalised through the canon, knowing water static pressure and abrasive mass rate. After the canon end the abrasive water-jet evolves in air and thus decelerates by friction. The tool-fluid adapts its geometric configuration from this kinetic energy decrease and impacts a target plane located at a known distance from the canon. Such a model is built on some classic process parameters as the water static pressure, the abrasive mass rate or the work-piece vs. canon distance, but it also naturally takes into account finer mechanical parameters as the abrasive granulometry or friction dissipation. Simulations gives interesting results of impact pressure distribution on the target work-piece with dynamic data of all the collection particles. More generally, this work final aim is to link elemental particle damage studies with a macroscopic wear prediction law.