A diffuse-interface method for simulating two-phase flows of complex fluids

Yue, Pengtao; Feng, James J.; Liu, Chun; Shen, Jie

doi:10.1017/s0022112004000370

Cited by 922 publications

(815 citation statements)

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“…Aside from this mathematical dilemma, the flow of multi-component complex fluids also involves the physical problem of microstructure-dependent rheology. Recently, we proposed a diffuseinterface model for two-phase flows of complex fluids that resolves both issues at once [16]. In this model, the two components are assumed to mix in a narrow interfacial layer, across which physical properties change steeply but continuously.…”

Section: Theoretical Model and Numerical Methodsmentioning

confidence: 99%

“…Yue et al [16] have given a detailed derivation of the model, described its numerical implementation using a spectral method and presented preliminary results for validation. We will only summarize the salient features here.…”

Section: Theoretical Model and Numerical Methodsmentioning

confidence: 99%

“…[16], one may derive the evolution equations for the configuration variables v, φ and n. Supplemented by the appropriate dissipative terms, these are essentially the governing equations familiar in the classical context,…”

Section: Theoretical Model and Numerical Methodsmentioning

confidence: 99%

“…Thus, we are using a simplified version of the Leslie-Ericksen theory [25]. These simplifications reflect a trade-off between capturing the complete physics and numerical convenience [16].…”

Section: Theoretical Model and Numerical Methodsmentioning

confidence: 99%

“…This paper represents our effort toward dynamic simulation of nematic-isotropic two-phase flows. We have previously developed a diffuse-interface formalism for two-phase flows of general complex fluids [16], and will apply the methodology to simulate an elongated nematic drop that retracts in a quiescent isotropic Newtonian fluid. Our rationale in choosing this problem is two-fold.…”

Section: Introductionmentioning

confidence: 99%

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Interfacial forces and Marangoni flow on a nematic drop retracting in an isotropic fluid

Yue

Feng

et al. 2005

Journal of Colloid and Interface Science

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Nematic-isotropic interfaces exhibit novel dynamics due to anchoring of the liquid crystal molecules on the interface. The objective of this study is to demonstrate the consequences of such dynamics in the flow field created by an elongated nematic drop retracting in an isotropic matrix. This is accomplished by two-dimensional flow simulations using a diffuse-interface model. By exploring the coupling among bulk liquid crystal orientation, surface anchoring and the flow field, we show that the anchoring energy plays a fundamental role in the interfacial dynamics of nematic liquids. In particular, it gives rise to a dynamic interfacial tension that depends on the bulk orientation. Tangential gradient of the interfacial tension drives a Marangoni flow near the nematic-isotropic interface. Besides, the anchoring energy produces an additional normal force on the interface that, together with the interfacial tension, determines the movement of the interface. Consequently, a nematic drop with planar anchoring retracts more slowly than a Newtonian drop, while one with homeotropic anchoring retracts faster than a Newtonian drop. The numerical results are consistent with prior theories for interfacial rheology and experimental observations.  2005 Elsevier Inc. All rights reserved.

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Section: Theoretical Model and Numerical Methodsmentioning

confidence: 99%

Section: Theoretical Model and Numerical Methodsmentioning

confidence: 99%

Section: Theoretical Model and Numerical Methodsmentioning

confidence: 99%

Section: Theoretical Model and Numerical Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Interfacial forces and Marangoni flow on a nematic drop retracting in an isotropic fluid

Yue

Feng

et al. 2005

Journal of Colloid and Interface Science

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A KDE‐Based Random Walk Method for Modeling Reactive Transport With Complex Kinetics in Porous Media

Sole‐Mari

Fernàndez-García

Rodríguez‐Escales

et al. 2017

Water Resources Research

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In recent years, a large body of the literature has been devoted to study reactive transport of solutes in porous media based on pure Lagrangian formulations. Such approaches have also been extended to accommodate second‐order bimolecular reactions, in which the reaction rate is proportional to the concentrations of the reactants. Rather, in some cases, chemical reactions involving two reactants follow more complicated rate laws. Some examples are (1) reaction rate laws written in terms of powers of concentrations, (2) redox reactions incorporating a limiting term (e.g., Michaelis‐Menten), or (3) any reaction where the activity coefficients vary with the concentration of the reactants, just to name a few. We provide a methodology to account for complex kinetic bimolecular reactions in a fully Lagrangian framework where each particle represents a fraction of the total mass of a specific solute. The method, built as an extension to the second‐order case, is based on the concept of optimal Kernel Density Estimator, which allows the concentrations to be written in terms of particle locations, hence transferring the concept of reaction rate to that of particle location distribution. By doing so, we can update the probability of particles reacting without the need to fully reconstruct the concentration maps. The performance and convergence of the method is tested for several illustrative examples that simulate the Advection‐Dispersion‐Reaction Equation in a 1‐D homogeneous column. Finally, a 2‐D application example is presented evaluating the need of fully describing non‐bilinear chemical kinetics in a randomly heterogeneous porous medium.

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Crowded Charges in Ion Channels

Eisenberg

2011

Advances in Chemical Physics

129

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Physical Chemistry and Life. Ions in water are the liquid of life. Life occurs almost entirely in 'salt water'. Life began in salty oceans. Animals kept that salt water within them when they moved out of the ocean to drier surroundings. The plasma and blood that surrounds all cells are electrolytes more or less resembling sea water. The plasma inside cells is an electrolyte solution that more or less resembles the sea water in which life began. Water itself (without ions) is lethal to animal cells and damaging for most proteins. Water must contain the right ions in the right amounts if it is to sustain life.Physical chemistry is the language of electrolyte solutions and so physical chemistry, and biology, particularly physiology, have been intertwined since physical chemistry was developed some one hundred fifty years ago. Physiology, of course, was studied by the Greeks some millennia earlier, but the biological role of electrolyte solutions could not be understood until ions were discovered by chemists some 2,000 years later.Physical chemists and biologists come from different traditions that separated for several decades as biologists identified and described the molecules of life. Communication is not easy between a fundamentally descriptive tradition and a fundamentally analytical one. Biologists have now learned to study their well defined systems with physical techniques, of considerable interest to physical chemists. Physical chemists are increasingly interested in spatially inhomogeneous systems with structures on the atomic scale so common in biology. Physical chemists will find it productive to work on well defined systems built by evolution to be reasonably robust, with input output relations insensitive to environmental insults. The overlap in science is clear. The human overlap is harder because the fields have grown independently for some time, and the knowledge base, assumptions, and jargon of the fields do not coincide. Indeed, they sometimes seem disjoint, without overlap.This article deals with properties of ion channels that in my view can be dealt with by 'physics as usual', with much the same tools that physical chemists apply to other systems. Indeed, I introduce and use a tool of physicists-a field theory (and boundary conditions) based on an energy variational approach developed by Chun Liu 141,575,766,806,944 -not too widely used among physical chemists. My goal is to provide the knowledge base, and identify the assumptions, that biologists use in studying ion channels, avoiding jargon. Although we do not know enough to write atomic, detailed physical models of the process by which ions move through channels, rather simple models of selectivity and permeation work quite well in important cases. Those physical models and cases are the main focus of this review because they demonstrate the strong essential link between the traditional treatments of ions in chemical physics, and the biological function of ion channels.At first, ion channels may seem to be an extreme system. They are as smal...

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A diffuse-interface method for simulating two-phase flows of complex fluids

Cited by 922 publications

References 64 publications

Interfacial forces and Marangoni flow on a nematic drop retracting in an isotropic fluid

Interfacial forces and Marangoni flow on a nematic drop retracting in an isotropic fluid

A KDE‐Based Random Walk Method for Modeling Reactive Transport With Complex Kinetics in Porous Media

Crowded Charges in Ion Channels

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