The topological complexity inherent to all porous media can impart complicated transport dynamics under steady flow conditions. Recently, it has been established [2] that such topological complexity imparts ubiquitous and persistent chaotic advection via a 3D fluid mechanical analogue of the baker’s map. In the presence of molecular diffusion, chaotic Lagrangian dynamics are well-known to impar...

A two-dimensional model for colloid transport in geochemically and physically heterogeneous porous media is presented. The model considers patchwise geochemical heterogeneity, which is suitable to describe the chemical variability of many surficial aquifers with ferric oxyhydroxide-coated porous matrix, as well as spatial variability of hydraulic conductivity, which results in heterogeneous flo...

Nowadays Nuclear Magnetic Resonance diffusion (dNMR) measurements of water molecules in heterogeneous systems have broad applications in material science, biophysics and medicine. Up to now, microstructural rearrangement in media has been experimentally investigated by studying the diffusion coefficient (D(t)) behavior in the tortuosity limit. However, this method is not able to describe struct...

Porous media with a wide distribution of pore sizes are quite common. We show that variable-step-size random walk simulations can be used to model the time-dependent diffusion coefficient D(t) in such porous media. The issue to be overcome is that, in variable-step-size walks, each walker carries its own "clock," and its position is known only at a random set of times. Thus, a direct ensemble-a...

We use Lattice Boltzmann models to simulate solute transport in porous media traversed by larger conduits and fit the resulting solute breakthrough curves with macroscopic Continuous Time Random Walk (CTRW) models. In this paper, the porous media are simulated using a real-numbered coefficient that partially damps the inertial components of the flow and, when the damping is large enough, leads ...

Statistical continuum approach is used to predict effective conductivity of anisotropic random porous heterogeneous media using twopoint correlation functions. Probability functions play a critical role in describing the statistical distribution of different constituents in a heterogeneous media. In this study a three-dimensional two-point correlation function is utilized to characterize the an...

The fundamental solution or Green's function for flow in porous media is determined using Stokesian dynamics, a molecular-dynamics-like simulation method capable of describing the motions and forces of hydrodynamically interacting particles in Stokes flow. By evaluating the velocity disturbance caused by a source particle on field particles located throughout a monodisperse porous medium at a g...

The random-walk method for simulating solute transport in porous media is typically based on the assumption that the velocity and velocity-dependent dispersion tensor vary smoothly in space. However, in cases where sharp interfaces separate materials with contrasting hydraulic properties, these quantities may be discontinuous. Normally, velocities are interpolated to arbitrary particle location...