Gaining control over the motion of colloids in complex environments is essential in a wide range of applications, from cell sorting and drug delivery to filtration and water purification. Recent studies have demonstrated the utility of diffusiophoresis, ie, the motion of colloids due to solute gradients, in manipulating and steering colloids in simple microfluidic geometries. Yet, it remains a...
Mixing in porous media and microfluidic devices can play a crucial role in various processes, including in-situ mining of minerals, geothermal heat extraction, and efficient operation of microreactors. However, such environments typically support flow at low Reynold’s numbers, so achieving controllable mixing can be challenging. To address this, electric fields can offer an externally...
Garrison Sposito’s “Chaotic Solute Advection by Unsteady Groundwater Flow” (Water Resources Research, 42, W06D03, https://doi.org/10.1029/2005WR004518, 2006) was the first in a growing body of literature exploring chaotic advection in porous media. In the nearly two decades since, this literature has provided new insights into solute transport, mixing, and reaction across multiple scales, from...
Solute transport in unsaturated media exhibits a complex, nonmonotonic dependence on fluid saturation and flow rates. Adding to the intricate dependence of multiphase flow and solute transport on the heterogeneity across scales is their coupling: the sensitivity of the concentration fields to the spatial distribution of the fluid phases and their velocity fields.
Here, we study solute...
Mixing limited reactions are highly influenced by the architecture of the geological deposits they flow through because the structured nature of the material can severely limit the ability of the reactants to mix. The complex patterns created by meandering and braided rivers result in sharp interfaces that interrupt correlation lengths and directions that are below the typical resolution of...
Predicting mineral reaction rates in porous media is challenging, in part due to the difficulty of accurately quantifying mineral reactive surface area. Mineral accessible surface area, the surface area of mineral phases in contact with reactive fluids, is an improved means of estimating mineral reactive surface area in multi-mineralic systems. Accessible mineral surface areas can be obtained...
The term ‘per- and polyfluoroalkylated substances’ (PFAS) refers to a broad class of molecules containing at least one perfluorinated methyl (-CF3) or methylene (- CF2-) group1. Their properties have led to their use in a large number of applications since the 1940s. Unfortunately, they are persistent in the environment or metabolised into persistent substances, bioaccumulative and harmful to...
In the literature, a range of theoretical approaches has been utilized to study solute transport through porous media. Among these, volume-averaging techniques developed by Whitaker and coworkers, alongside probabilistic methods introduced by Brenner and coworkers, have become prominent within the research community. While these approaches have proven useful, they encounter significant...
Geological Carbon Sequestration and Underground Hydrogen Storage in porous reservoirs are promising strategies for transitioning to clean energy production. Gas dissolution in brine significantly influences flow and trapping behavior during both CO2 and H2 storage in porous reservoirs. Interestingly, for H2 storage, this effect was unexpected due to hydrogen's low solubility in brine....
Efficient solute mixing in porous media is crucial for various natural processes and industrial applications, such as nutrient transport in biological systems, groundwater bioremediation, carbon dioxide-enhanced oil recovery, and packed-bed reactors. The effectiveness of solute mixing directly influences the rates of biological and chemical reactions in these scenarios. While turbulence is...
We investigate the mixing dynamics of a large solute plume transported by advection and local diffusion in Darcy-scale porous formations characterized by randomly heterogeneous distributions of hydraulic conductivity. We test the dispersive lamella mixing model for mildly to highly heterogeneous formations. At the core of the dispersive lamella mixing model lays a single non-interacting...
A hyperbolic description of the problem of solute transport using a deterministic and Lagrangian formulation that combines characteristics of the classical formulations based on the Fokker-Planck (FP) and Langevin equations is developed. This formulation is based on a Liouville master equation, whose hyperbolicity allows for tracing the concentrations along characteristic lines in the...
River corridor beds are often comprised of distinguishable subdomains such as the benthic biolayer and the underlying hyporheic zone. Mixing between streamwater and groundwater, that controls reaction extent for a variety of biogeochemical transformations, can occur at dramatically different rates in the different domains including the stream, the benthic layer, the hyporheic zone, or any...
When concentration or temperature contrast results in higher fluid density at the top of a porous stratum than that at the bottom of a porous stratum, buoyancy may drive Rayleigh-Darcy (R-D) convection that fundamentally shapes the transport and reactive dynamics. R-D convection commonly emerges in CO2 sequestration and in stratums with high geothermal gradient. Regardless of numerous studies...
Many theoretical treatments of transport in heterogeneous Darcy flows consider advection only. When local-scale dispersion is neglected, flux weighting persists over time; mean Lagrangian and Eulerian flow velocity distributions relate simply to each other and to the variance of the underlying hydraulic conductivity field. Local-scale dispersion complicates this relationship, potentially...
