Gravity fingering is a hallmark instability during infiltration into dry porous media, where small perturbations in the wetting front amplify into preferential flow paths that strongly influence water and solute transport in soils. Despite decades of numerical and laboratory investigations, a persistent challenge has been directly linking pore-scale invasion mechanisms to the macroscopic...
The size of a pendant drop detaching from a capillary is classically set by the balance between gravity and surface tension, as described by Tate’s law, implying only a weak dependence on nozzle size. We show that purely geometric confinement provides a simple and robust means to tune the detachment volume well below this classical limit. By placing a capillary between two superhydrophobic...
Multiphase flow in porous media strongly depends on the apparent wettability. Common approaches for characterizing static apparent wettability include the captive bubble and sessile drop methods, while dynamic contact angles are commonly measured using the tilted plate method. Interestingly, pressure and temperature dependencies have been reported for various gas-water systems using the tilted...
Due to their potential for long durability, ceramic membranes are currently being investigated for various hydrogen-related applications [1]. One of the challenges in developing novel membranes is controlling the porous structures to achieve high hydrogen permeation without compromising their structural stability. During sintering, a technique in which solid ceramic powders are heated to high...
In this study, we investigate the interplay between capillarity, gas dissolution and salt crystallization (capillarity-crystallization dynamics) within novel, reproducible, and depth-variable (2.5D) polydimethylsiloxane (PDMS)-glass microfluidic channels with controlled submicron features. These channels more accurately replicate varied pore throat morphologies found in geologic and other...
Describing the transport of scalars such as nutrients and contaminants in heterogeneous systems presents both computational and modeling challenges and can lead to a rich set of behaviors across different scales. Random walk particle tracking methods offer an alternative to more traditional Eulerian approaches that involves discretizing the transported plume into point masses. Each resulting...
Mineral nucleation dictates the areas within porous media where secondary minerals form and grow, and in turn, how fluid flow is affected by the growth. Recently, probabilistic treatments of mineral nucleation in reactive transport models (RTM) have provided insights into how factors such as supersaturation and pore-space characteristics affect the spatial pattern of mineral nucleation and...
Stalagmites are a classic example of a natural reactive transport system, where the evolution of the solid domain is coupled to the hydrodynamics of a thin fluid film and the precipitation kinetics of calcium carbonate. Nearly sixty years ago, Franke [1] formulated a mathematical model for this process, effectively casting it as a thin-film transport and reaction problem on a moving boundary....
Reactive viscous fingering in porous media differs fundamentally from nonreactive miscible displacement because chemical reactions can sustain traveling fronts with fixed width and speed. As shown by A. De Wit (Phys. Rev. Lett., 2001), this property leads to time-independent dispersion relations under steady forcing, in contrast to purely diffusive fronts whose stability evolves in time....
Microbially induced calcite precipitation (MICP) is used as a reinforcement technique in non-cohesive soils. Sporosarcina pasteurii bacteria induce the precipitation of calcite crystals in the pores, which bond grains together and turn sand into a cohesive medium [a,b]. One of the challenges associated with industrial development of the technique is the characterisation of the material...
Salt creeping is a phenomenon where salt crystals continue to precipitate far from an evaporating salt solution by a self-amplifying mechanism. Due to multiple nucleation sites of crystallization at the evaporation front , the spreading of the salt solution is enhanced well beyond the initial liquid/air front and creates a self-amplifying process[1]. The process results in three-dimensional...
Understanding particle-influenced evaporation in porous media is crucial for various industrial processes, including battery electrode preparation, where active particles form a framework while solutes redistribute, ultimately determining the material’s functional performance. However, predicting such behavior is challenging due to the complex coupling between capillary forces, evaporation...
Understanding the evaporation and imbibition of surfactant-laden droplets on porous media is both scientifically challenging and industrially important, such as in inkjet printing applications. In inkjet printing, a uniform ink deposition pattern and prevention of droplet coalescence are desirable for high print quality. The addition of surfactants can alter the surface tension at the...
The evaporation of a liquid from within a porous material is a multi-phase, interfacial flow process involving coupled vapour diffusion, phase-change, and capillary flow. Mass transfer across the microscale water-air interfaces drives the macroscale porous-medium flow. Typically, different drying behaviours are seen at different stages in the drying process. When capillary forces dominate,...
The study of the crystallization of one or more salts resulting from evaporation from a porous medium has motivated numerous works, see [1] and references therein. However, a systematic study of the impact of the evaporation conditions and the mean pore size of the porous medium is still lacking. In order to fill this gap, we are performing an experimental campaign for aqueous solutions of...
We investigate evaporation in heterogenous porous media via microfluidic experiments and simulations. In a single column filled with a volatile liquid and exposed to air, vapour transport to the column exit will be diffusively limited, and the liquid height and hence evaporation rate will decrease as the square root of time. When multiple columns or channels of different diameters are linked,...
Per- and polyfluoroalkyl substances (PFAS) are emerging contaminants that are ubiquitous in the environment, with their fate and transport strongly influenced by adsorption at the air–water interface. Accurate quantification of air–water interfacial adsorption is therefore critical for understanding PFAS migration in environmental systems involving air–water interfaces. However, PFAS...
Two-phase flow in unconsolidated granular media is a common process. It takes place during rain infiltration in soils, in sandcastles, and numerous situations in the critical zone.
The mechanical stability of slopes and materials is expressed by considering stability envelope of the stress tensor supported by the solid material. In one phase flow, this leads to criterias on Terzaghi stress,...
PFAS (per- and polyfluoroalkyl substances) have emerged as environmentally persistent compounds in water resources, of global concern due to their mobility, bioaccumulation, and toxicity. In this work, we demonstrate two unique pilot-scale experimental platforms to evaluate the efficiency of different adsorption mechanisms for enhanced PFAS removal: 1) down-flow filtration through fixed-bed...
Cation exchange, adsorption, and desorption kinetics at soil-water interfaces have been investigated for many years. Some experiments observed that the rate constant varies with flow conditions. This behavior is commonly attributed to transport limitations within the porous medium. However, recent work of Werkhoven et al. (2018) have shown that flow can induce strong lateral heterogeneity in...
Modeling multicomponent multiphase (MCMP) flows in confined disordered media requires a tight, consistent coupling between thermodynamics, which controls phase behavior, phase transformations, and interfacial properties, and hydrodynamics, which governs transport and momentum exchange across complex pore geometries. Despite significant progress in both areas, the robust coupling of...
