Dynamics and thin film drainage of a deformable droplet moving towards a solid wall with finite inertia

In many multiphase fluidic processes, such as in petroleum extraction and biochemical analysis involving microscale conduits, the lodging of immiscible droplets often leads to disastrous flow blockage. Without a thin-film lubrication layer surrounding the adhered droplets, a significantly higher threshold pressure gradient is required to reinitiate bulk flows. In this work, we investigate the surface tension-driven thin-film drainage process that leads to droplet adhesion and study how electrostatic repulsion between a charged droplet interface and a charged conduit wall can prevent direct contact between the two. We report on our multiphysics computational results of an oversized gas droplet in a water-filled flow microchannel under the influence of surface tension and interfacial electrostatic forces.

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Molecular Dynamics Simulation of Normal and Explosive Boiling on Nanostructured Surface

Journal of Heat Transfer ◽

10.1115/1.4024668 ◽

2013 ◽

Vol 135 (12) ◽

Cited By ~ 33

Author(s):

Hamid Reza Seyf ◽

Yuwen Zhang

Keyword(s):

Thin Film ◽

Molecular Dynamics ◽

Evaporation Rate ◽

Solid Wall ◽

Molecular System ◽

Spherical Shape ◽

Dynamics Simulation ◽

Spherical Particles ◽

Explosive Boiling ◽

Higher Temperature

Molecular Dynamics (MD) simulation is carried out to investigate the normal and explosive boiling of thin film adsorbed on a metal substrate whose surface is structured by an array of nanoscale spherical particles. The molecular system is comprised of the liquid and vapor argon as well as a copper wall. The nanostructures have spherical shape with uniform diameters while the thickness of liquid film is constant. The effects of transvers and longitudinal distances as well as the diameter of nanoparticles are analyzed. The simulation is started from an initial configuration for three phases (liquid argon, vapor argon and solid wall); after equilibrating the system at 90 K, the wall is heated suddenly to a higher temperature that is well beyond the critical temperature of argon. Two different superheat degrees are selected: a moderately high temperature of 170 K for normal evaporation and much higher temperature 290 K for explosive boiling. By monitoring the space and time dependences of temperature and density as well as net evaporation rate, the normal and explosive boiling process on a flat surface with and without nanostructures are investigated. The results show that the nanostructure has significant effect on evaporation/boiling of thin film. The degrees of superheat and size of nanoparticles have significant effects on the trajectories of particles and net evaporation rate. For the cases with nanostructure, liquid responds very quickly and the number of evaporation molecules increases with increasing the size of particles from 1 to 2 nm while it decreases for d = 3 nm.

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Numerical simulation for a rising bubble interacting with a solid wall: Impact, bounce, and thin film dynamics

Physics of Fluids ◽

10.1063/1.5055671 ◽

2018 ◽

Vol 30 (11) ◽

pp. 112106 ◽

Cited By ~ 4

Author(s):

Changjuan Zhang ◽

Jie Li ◽

Li-Shi Luo ◽

Tiezheng Qian

Keyword(s):

Thin Film ◽

Numerical Simulation ◽

Solid Wall ◽

Rising Bubble

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The effect of solid wall interaction on an amorphous polyethylene thin film, using a Monte Carlo simulation on a high coordination lattice

Polymer ◽

10.1016/s0032-3861(99)00071-3 ◽

1999 ◽

Vol 40 (16) ◽

pp. 4685-4694 ◽

Cited By ~ 22

Author(s):

J.H. Jang ◽

W.L. Mattice

Keyword(s):

Thin Film ◽

Monte Carlo Simulation ◽

Monte Carlo ◽

Solid Wall ◽

Wall Interaction ◽

High Coordination

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Flow characteristics and a permeability model in nanoporous media with solid-liquid interfacial effects

Interpretation ◽

10.1190/int-2016-0009.1 ◽

2017 ◽

Vol 5 (1) ◽

pp. SB1-SB8 ◽

Cited By ~ 2

Author(s):

Jiulong Wang ◽

Hongqing Song ◽

Weiyao Zhu ◽

Yuhe Wang ◽

John Killough

Keyword(s):

Thin Film ◽

Solid Wall ◽

Flow Characteristics ◽

Average Pore ◽

Flow Rates ◽

Interfacial Effects ◽

Nanoporous Media ◽

Flow Through ◽

Repulsive Forces ◽

Solid Liquid

Molecular dynamics simulations of water flow through nanotubes have demonstrated higher flow rates than the flow rates predicted using classical models and a significant change in flow patterns due to the thin film that forms on the solid wall of the tubes. We have developed a two-region analytical model that described the flow characteristics and permeability of fluid flow through nanoporous media and considered the solid-liquid interfacial effects. Our model considers the influence of various interfacial effects, including long-range van der Waals forces, double-layer repulsive forces, and short-range structure repulsive forces, and it establishes relationships between the permeability and the average pore diameter, porosity, surface diffusion, and contact angle by numerical calculations. Our results indicate that the permeability calculated using the present model (with interfacial effects) is more than 30 times the results that were calculated using the Kozeny-Carman equation (without interfacial effects). The thickness of the thin film significantly affects the flow characteristics. We have gained new insight and guidance regarding the development of nanoscale pore reservoirs, such as shale gas and shale oil.

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