We develop a novel ‘moving-capacitor’ dynamic network model to simulate immiscible fluid–fluid displacement in porous media. Traditional models approximate the pore geometry as of fixed resistors, directly analogous an electrical circuit. Our additionally captures motion individual interfaces through by completing this analogy, representing set moving capacitors. By incorporating pore-scale invasion events, reproduces, for first time, both pattern and injection-pressure signal under wide...

Abstract

An examination of the concentration a pathogen exhaled while speaking in poorly ventilated space suggests that probability infection is relatively high for few minutes contact time at separation 1 meter distance and double 2 meters.

Immiscible fluid-fluid displacement in partial wetting continues to challenge our microscopic and macroscopic descriptions. Here, we study the of a viscous fluid by less circular capillary tube regime. In contrast with classic results for complete wetting, show that presence moving contact line induces transition at critical number is angle dependent. At small rates, interface deforms slightly from its equilibrium state moves downstream constant velocity, without changing shape. As rate...

Small multicomponent droplets are of increasing importance in a plethora technological applications ranging from the fabrication self-assembled hierarchical patterns to design autonomous fluidic systems. While often far away equilibrium, involving complex and even chaotic flow fields, it is commonly assumed that these systems with small drops surface tension keeps shapes spherical. Here, studying picoliter volatile binary-mixture isopropanol 2-butanol, we show dominance forces at scales can...

The dependence of velocity slip at a liquid-solid interface upon the character solid is studied using atomistic simulation methods for Lennard-Jones model systems. effect thermostatting mechanisms, often used in such simulations, also investigated. atom vibrational frequency shown not to have significant on length range parameters investigated; however, it found that application thermostat fluid changes low shear rates and results an unphysical divergent behavior high rates. On other hand,...

A uniform nanometric thin liquid film on a solid substrate can become unstable due to the action of van der Waals (vdW) forces. The instability leads dewetting and formation drops. To minimize total free energy system, these drops coarsen over time until one single drop remains. Here, using thermodynamically consistent framework, we derive new model for films in partial wetting with that resembles Cahn–Hilliard form height-dependent surface tension generalized disjoining pressure, revisit...

Solute gradients next to an interface drive a diffusioosmotic flow, the origin of which lies in intermolecular interactions between solute and interface. These flows on surface colloids introduce effective slip velocity, driving their diffusiophoretic migration. In confined environments, interplay diffusiophoresis diffusioosmosis governs motion colloids. Previous studies have indeed demonstrated quantitative modulation phoretic migration by osmotic flows. Here, we show that can lead...

For almost 200 y, the dominant approach to understand oil-on-water droplet shape and stability has been thermodynamic expectation of minimized energy, yet parallel literature shows prominence Marangoni flow, an adaptive gradient interfacial tension that produces convection rolls in water. Our experiments, scaling arguments, linear analysis show resulting Marangoni-driven high-Reynolds-number flow shallow water overcomes radial symmetry otherwise enforced by Laplace pressure. As a...

Immiscible fluid-fluid displacement in confined geometries is a fundamental process occurring many natural phenomena and technological applications, from geological CO2 sequestration to microfluidics. Due the interactions between fluids solid walls, fluid invasion undergoes wetting transition complete at low rates leaving film of defending on confining surfaces high rates. While most real are rough, questions remain about type that can emerge confined, rough geometry. Here, we study...

Droplets of alcohol-based formulations are common in applications from sanitizing sprays to printing inks. However, our understanding the drying dynamics these droplets on surfaces and influence ambient humidity is still very limited. Here, we report picoliter isopropyl alcohol deposited a surface under controlled humidity. Condensation water vapor environment onto leads unexpectedly complex behavior. As relative (RH) increases, observed variety phenomena including enhanced spreading,...

When a liquid touches solid surface, it spreads to minimize the system's energy. The classic thin-film model describes spreading as an interplay between gravity, capillarity, and viscous forces, but cannot see end this process does not account for nonhydrodynamic liquid-solid interactions. While these interactions are important only close contact line, where liquid, solid, gas meet, they have macroscopic implications: in partial-wetting regime, puddle ultimately stops spreading. We show that...

The effects of an external shear flow on the dynamics and pattern formation in a dilute suspension swimming micro-organisms are investigated using linear stability analysis three-dimensional numerical simulations, based kinetic model previously developed by [D. Saintillan M. J. Shelley, Phys. Fluids 20, 123304 (2008)]. is found to damp instabilities that occur these suspensions controlling orientation particles. We demonstrate our simulations rate damping direction-dependent: it fastest...

A kinetic model and three-dimensional numerical simulations are applied to study the dynamics in suspensions of run-and-tumble aerotactic bacteria confined free-standing liquid films surrounded by air. In thin films, oxygen bacterial concentration profiles approach steady states. thicker a transition chaotic is shown occur characterized unsteady correlated motions, formation plumes, enhanced transport consumption. This transition, also observed previous experiments, arises as result coupling...

Significance We observe the formation of bubbles and drops on a daily basis, from dripping faucets to raindrops entraining surface lake. The ubiquity phenomenon masks fascinating underlying nonlinear dynamics that is such an important aspect modern physics. Here, we report surprising observation confinement makes pinch-off bubble universal process, as opposed unconfined case, where sensitive details experimental setting. explain how motion contact line, liquid, gas, solid phases meet, leads...

Understanding how colloids move in crowded environments is key for gaining control over their transport applications such as drug delivery, filtration, contaminant/microplastic remediation and agriculture. The classical models of colloid porous media rely on geometric characteristics the medium, hydrodynamic/non-hydrodynamic equilibrium interactions to predict behavior. However, chemical gradients are ubiquitous these can lead non-equilibrium diffusiophoretic migration colloids. Here,...

When one fluid displaces another in a confined environment, some energy is dissipated the bulk and rest near contact line. Here we study relative strengths of these two sources dissipation with novel experimental setup: constant-rate spontaneous imbibition experiments, achieved by introducing viscous oil slug front invading inside capillary tube. We show that large fraction can take place line, rationalize observations means theoretical analysis dynamic angles back menisci slug. Our results...

Coalescence and breakup of drops are classic problems in fluid physics that often involve self-similarity singularity formation. While the coalescence suspended is axisymmetric, on a substrate inherently three-dimensional. Yet, studies so far have only considered this problem two dimensions. In Letter, we use interferometry to reveal three-dimensional shape interface as substrate. We unify known scaling laws within thin-film approximation find enables us describe anisotropic dynamic with...

During mesenchymal migration, F-actin protrusion at the leading edge and actomyosin contraction determine retrograde flow of within lamella. The coupling this to integrin-based adhesions determines force transmitted extracellular matrix net motion cell. In tissues, may also arise from convection, driven by gradients in tissue-scale surface tensions pressures. However, how migration coordinates with convection cellular ensembles is unclear. To explore this, we study spreading cell aggregates...