Fluid Interfaces during Viscous-Dominated Primary Drainage in 2D Micromodels Using Pore-Scale SPH Simulations

Abstract

We perform pore-scale resolved direct numerical simulations of immiscible two-phase flow in porous media to study the evolution of fluid interfaces. Using a Smoothed-Particle Hydrodynamics approach, we simulate saturation-controlled primary drainage in heterogeneous, partially wettable 2D porous microstructures. While imaging the evolution of fluid interfaces near capillary equilibrium becomes more feasible as fast X-ray tomography techniques mature, imaging methods with suitable temporal resolution for viscous-dominated flow have only recently emerged. In this work, we study viscous fingering and stable displacement processes. During viscous fingering, pore-scale flow fields are reminiscent of Bretherton annular flow, that is, the less viscous phase percolates through the core of a pore-throat forming a hydrodynamic wetting film. Even in simple microstructures wetting films have major impact on the evolution of fluid interfacial area and are observed to give rise to nonnegligible interfacial viscous coupling. Although macroscopically appearing flat, saturation fronts during stable displacement extend over the length of the capillary dispersion zone. While far from the dispersion zone fluid permeation obeys Darcy's law, the interplay of viscous and capillary forces is found to render fluid flow within complex. Here we show that the characteristic length scale of the capillary dispersion zone increases with the heterogeneity of the microstructure.

The Effect of Wettability and Flow Rate on Oil Displacement Using Polymer-Coated Silica Nanoparticles: A Microfluidic Study

“…Table 4 presents the contact angles resulting from the interactions between SSW/NF, oil, and glass substrates of different wettability conditions. In this study, the magnitude of change in contact angle of 11.4 • and 43.9 • for water-and intermediate-wet substrates, respectively, is comparable to reported results in previous work [35][36][37][38]. The magnitude of change in the contact angle of 97.55 • for an oil-wet substrate with a percent reduction of 66.67%, proves that the used PSiNPs are strongly capable of reducing the oil's ability to maintain contact with an oil-wet medium.…”

Pore-scale effects during the transition from capillary- to viscosity-dominated flow dynamics within microfluidic porous-like domains

“…This approach offers a more rigorous method to study pore-scale physics under a wide variety of flow conditions, at the expense, however, of significant computational resources and time. Such approaches include highly parallel Lattice Boltzmann methods [40][41][42][43][44] , which are however limited to relative small density differences and a restricted choice of boundary conditions to generate flow, Particle-Hydrodynamics (SPH) [45][46][47] , the Volume-of-Fluid (VOF) method 48,49 , Level-Set, and Phase Field approaches 50,51 . Such contributions have offered significant insight on pore-scale physics that determine the temporal evolution of interfaces under a wide range of flow conditions.…”

Modelling of Non-Spherical Particles in Dilute Non-Colloidal Suspensions Using SPH

“…For the purpose of studying the effects of heterogeneous particles in a single-phase fluid, we employ pore-scale resolved Direct Numerical Simulations (DNS). Our method of choice is Smoothed Particle Hydrodynamics (SPH) using an implementation that has previously been shown to accurately reproduce effective hydraulic properties of porous media [27][28][29]. In particular, our implementation incorporates the SPH scheme proposed in [14] together with the boundary conditions proposed in [30] and presents an extension of the highly optimized Molecular Dynamics software HOOMD-blue [16,17].…”