Particle clusters at fluid–fluid interfaces: equilibrium profiles, structural mechanics and stability against detachment

Soft Matter ◽  
2019 ◽  
Vol 15 (24) ◽  
pp. 4921-4938 ◽  
Author(s):  
Jan Guzowski ◽  
Bopil Gim
Keyword(s):  
Contact Angle ◽  
Body Force ◽  
Structural Mechanics ◽  
Fluid Interfaces ◽  
Equilibrium Profiles ◽  
The Stability ◽  
Number Of Particles ◽  
External Body

We investigate the stability of interfacial particle clusters aggregating under an external body force depending on the number of particles and the contact angle.

scholarly journals Floating and sinking of self-assembled spheres on liquid-liquid interfaces: rafts versus stacks

2021 ◽  
Author(s):  
Steven G. Jones ◽  
Niki Abbasi ◽  
Abhinav Ahuja ◽  
Vivian Truong ◽  
Scott S. H. Tsai
Keyword(s):  
Critical Size ◽  
Bond Number ◽  
Fluid Interfaces ◽  
Liquid Interfaces ◽  
Dimensionless Ratio ◽  
Oil Water ◽  
Self Assembled ◽  
Size Limits ◽  
The Stability ◽  
Number Of Particles

The floating and sinking of objects on fluid-fluid interfaces occurs in nature, and has many important implications in technology. Here, we study the stability of floating self-assembled spheres on an oil-water interface, and how the sphere deposition geometry affects the size limits of the assemblies before they collapse and sink through the interface. Specifically, we compare the critical size of particle rafts to particle stacks. We show that, on liquid-liquid interfaces, monolayer rafts and stacked sphere exhibit different scaling of the critical number of spheres to the Bond number - the dimensionless ratio of buoyancy to interfacial tension effects. Our results indicate that particle stacks will sink with a lower threshold number of particles than particle rafts. This finding may have important implications to engineering applications where interfacial assemblies are not monolayers.

scholarly journals Floating and sinking of self-assembled spheres on liquid-liquid interfaces: rafts versus stacks

2021 ◽  
Author(s):  
Steven G. Jones ◽  
Niki Abbasi ◽  
Abhinav Ahuja ◽  
Vivian Truong ◽  
Scott S. H. Tsai
Keyword(s):  
Critical Size ◽  
Bond Number ◽  
Fluid Interfaces ◽  
Liquid Interfaces ◽  
Dimensionless Ratio ◽  
Oil Water ◽  
Self Assembled ◽  
Size Limits ◽  
The Stability ◽  
Number Of Particles

The floating and sinking of objects on fluid-fluid interfaces occurs in nature, and has many important implications in technology. Here, we study the stability of floating self-assembled spheres on an oil-water interface, and how the sphere deposition geometry affects the size limits of the assemblies before they collapse and sink through the interface. Specifically, we compare the critical size of particle rafts to particle stacks. We show that, on liquid-liquid interfaces, monolayer rafts and stacked sphere exhibit different scaling of the critical number of spheres to the Bond number - the dimensionless ratio of buoyancy to interfacial tension effects. Our results indicate that particle stacks will sink with a lower threshold number of particles than particle rafts. This finding may have important implications to engineering applications where interfacial assemblies are not monolayers.

Dependence of the Contact Angle on Adsorption at the Solid-Liquid Interface

2010 ◽  
Author(s):  
C. A. Ward
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Pressure Range ◽  
Line Tension ◽  
Liquid Interface ◽  
Fluid Interfaces ◽  
Phase Line ◽  
Three Phase ◽  
Solid Liquid Interface ◽  
Solid Liquid

A method for determining the surface tension of solid-fluid interfaces has been proposed. For a given temperature and fluid-solid combination, these surface tensions are expressed in terms of material properties that can be determined by measuring the amount of vapor adsorbed on the solid surface as a function of xV, the ratio of the vapor-phase pressure to the saturation-vapor pressure. The thermodynamic concept of pressure is shown to be in conflict with that of continuum mechanics, but is supported experimentally. This approach leads to the prediction that the contact angle, θ, can only exist in a narrow pressure range and that in this pressure range, the solid-vapor surface tension is constant and equal to the surface tension of the liquid-vapor interface, γLV. The surface tension of the solid-liquid interface, γSL, may be expressed in terms of measurable properties, γLV and θ: γSL = γLV(1 − cosθ). The value of θ is predicted to depend on both the pressure in the liquid at the three-phase, line x3L, and the three-phase line curvature, Ccl. We examine these predictions using sessile water droplets on a polished Cu surface, maintained in a closed, constant volume, isothermal container. The value of θ is found to depend on the adsorption at the solid-liquid interface, nSL = nSL(x3L,Ccl). The predicted value of θ is compared with that measured, and found to be in close agreement, but no effect of line tension is found.

scholarly journals A spherical particle straddling a fluid/gas interface in an axisymmetric straining flow

1990 ◽  
Vol 217 ◽  
pp. 263-298 ◽  
Author(s):  
J. A. Stoos ◽  
L. G. Leal
Keyword(s):  
Contact Angle ◽  
Spherical Particle ◽  
Numerical Solutions ◽  
Contact Angles ◽  
Boundary Integral ◽  
Equilibrium Contact Angle ◽  
Equilibrium Configurations ◽  
Wide Range ◽  
The Stability ◽  
Neutrally Buoyant

Numerical solutions, obtained via the boundary-integral technique, are used to consider the effect of a linear axisymmetric straining flow on the existence of steady-state configurations in which a neutrally buoyant spherical particle straddles a gas–liquid interface. The problem is directly applicable to predictions of the stability of particle capture in flotation processes, and is also of interest in the context of contact angle and surface tension measurements. A primary goal of the present study is a determination of the critical capillary number, Cac, beyond which an initially captured particle is pulled from the interface by the flow, and the dependence of Cac on the equilibrium contact angle θc. We also present equilibrium configurations for a wide range of contact angles and subcritical capillary numbers.

The stability of pendent liquid drops. Part 1. Drops formed in a narrow gap

1973 ◽  
Vol 59 (4) ◽  
pp. 753-767 ◽  
Author(s):  
E. Pitts
Keyword(s):  
Contact Angles ◽  
Two Dimensional ◽  
Narrow Gap ◽  
Cross Sectional ◽  
Liquid Drops ◽  
Maximum Area ◽  
Area Increase ◽  
Equilibrium Profiles ◽  
The Stability ◽  
Horizontal Support

We consider a drop of liquid hanging from a horizontal support and sandwiched between two vertical plates separated by a very narrow gap. Equilibrium profiles of such ‘two-dimensional’ drops were calculated by Neumann (1894) for the case when the angle of contact between the liquid and the horizontal support is zero. This paper gives the equilibrium profiles for other contact angles and the criterion for their stability. Neumann showed that, as the drop height increases, its cross-sectional area increases until a maximum is reached. Thereafter, as the height increases, the equilibrium area decreases. This behaviour is shown to be typical of all contact angles. When the maximum area is reached, the total energy is a minimum. It is shown that the drops are stable as long as the height and the area increase together.

Contact angle of micro- and nanoparticles at fluid interfaces

2014 ◽  
Vol 19 (4) ◽  
pp. 355-367 ◽  
Author(s):  
Armando Maestro ◽  
Eduardo Guzmán ◽  
Francisco Ortega ◽  
Ramón G. Rubio
Keyword(s):  
Contact Angle ◽  
Fluid Interfaces

Two-dimensional turbulence near the viscous limit

1974 ◽  
Vol 62 (2) ◽  
pp. 273-287 ◽  
Author(s):  
J. S. A. Green
Keyword(s):  
Steady State ◽  
Kinetic Energy ◽  
Body Force ◽  
Reynolds Numbers ◽  
Rapid Decrease ◽  
Two Dimensional ◽  
Turbulent Stress ◽  
Viscous Limit ◽  
External Body

Two-dimensional incompressible motion is generated by a steady external body force varying sinusoidally with a transverse co-ordinate. Such flow is found to be unstable for Reynolds numbers greater than 2½, and under these conditions evolves towards a new steady state. This ‘steady-eddy’ state is itself unstable in a sense, and its breakdown suggests the catastrophic onset of a cascade of turbulence. The mechanics of this cascade can be represented by a kind of recursion system in which the turbulence dynamics of one scale is repeated in the next, and a law of turbulent stress results. The spectrum of kinetic energy generated by a steady input of momentum at a discrete wavelength shows a rapid decrease (as k−5) towards shorter wavelengths but a much slower decrease (as k) towards longer wavelengths.

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