Wetting transitions within membrane compartments

The wetting transitions from complete to partial wetting and to complete dewetting are identified within a membrane compartment. The dependences of wetting transitions on material parameters, such as the intrinsic contact angles, the interaction strengths between the polymers and between the membrane and polymer ηp, and impermeability of the membrane to the enclosed polymers, are investigated.

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Micro/Meso Scale Modelling of Two-Phase Flow on Functional Surfaces: A Numerical Simulation of Water Droplets on Natural Hydrophobic Surfaces With Micro Roughness

ASME 2009 7th International Conference on Nanochannels, Microchannels and Minichannels ◽

10.1115/icnmm2009-82155 ◽

2009 ◽

Author(s):

Y. Y. Yan

Keyword(s):

Two Phase Flow ◽

Contact Angles ◽

Phase Flow ◽

Fluid Interface ◽

Water Droplets ◽

Hydrophobic Surfaces ◽

Two Phase ◽

Partial Wetting ◽

Scale Modelling ◽

Meso Scale

A micro/meso scale modelling of two-phase droplets move on hydrophilic/hydrophobic surfaces with micro roughness is reported. The physical model is basically of two-phase flow interacting with the surfaces of different hydrophobicity or wettability. Numerical modelling based on the lattice Boltzmann method (LBM) is developed and applied to the computational calculation and simulation. The LBM modelling deals with surface tension dominated behaviour of water droplets in air spreading on a hydrophilic surface with hydrophobic strips of different sizes and contact angles under different physical and interfacial conditions, and aims to find quantitative data and physical conditions of the biomimetic approaches. The current LBM can be applied to simulate two-phase fluids with large density ratio (up to 1000), and meanwhile deal with interactions between a fluid-fluid interface and a partial wetting wall. In the simulation, the interactions between the fluid-fluid interface and the partial wetting wall with different hydrophobic strips such as single strip, intersecting stripes, and alternating & parallel stripes, of different sizes and contact angles are considered and tested numerically; the phenomena of droplets spreading and breaking up, and the effect of hydrophobic strips on the surface wettability or self-cleaning characteristics are simulated, reported and discussed.

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Regimes of thermocapillary migration of droplets under partial wetting conditions

Journal of Fluid Mechanics ◽

10.1017/s0022112010000078 ◽

2010 ◽

Vol 647 ◽

pp. 125-142 ◽

Cited By ~ 30

Author(s):

J. M. GOMBA ◽

G. M. HOMSY

Keyword(s):

Contact Angle ◽

Leading Edge ◽

Contact Angles ◽

Two Dimensional ◽

Thickness Profile ◽

Heated Substrate ◽

Thermocapillary Migration ◽

Partial Wetting ◽

Pressure Term ◽

Film Profile

We study the thermocapillary migration of two-dimensional droplets of partially wetting liquids on a non-uniform heated substrate. An equation for the thickness profile of the droplet is derived by employing lubrication approximations. The model includes the effect of a non-zero contact angle introduced through a disjoining–conjoining pressure term. Instead of assuming a fixed shape for the droplet, as in previous works, here we allow the droplet to change its profile with time. We identify and describe three different regimes of behaviour. For small contact angles, the droplet spreads into a long film profile with a capillary ridge near the leading edge, a behaviour that resembles the experiments on Marangoni films reported by Ludviksson & Lightfoot (Am. Inst. Chem. Eng. J., vol. 17, 1971, pp. 1166). For large contact angles, the droplet moves as a single entity, weakly distorted from its static shape. This regime is the usual one reported in experiments on thermocapillary migration of droplets. We also show some intriguing morphologies that appear in the transition between these two regimes. The occurrence of these three regimes and their dependence on various parameters is analysed.

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Molecular Dynamics Study of Adsorption of the Lennard-Jones Truncated and Shifted Fluid on Planar Walls

10.31219/osf.io/v9ujs ◽

2021 ◽

Author(s):

Michaela Heier ◽

Felix Diewald ◽

Martin Horsch ◽

Kai Langenbach ◽

Ralf Müller ◽

...

Keyword(s):

Molecular Dynamics ◽

Gas Phase ◽

Saturation Pressure ◽

Contact Angles ◽

Surface Excess ◽

Lennard Jones ◽

Partial Wetting ◽

Adsorbed Layers ◽

Cutoff Radius ◽

Fluid Interaction

A comprehensive molecular dynamics study of gas phase and supercritical fluid adsorption on planar walls in dispersive systems is presented. All interactions in the system are described with the Lennard-Jones truncated and shifted (LJTS) potential with a cutoff radius of 2.5 fluid diameters. The adsorption strength is characterized by the solid-fluid interaction energy and the wall density. Both parameters are varied systematically. The present work extends a previous study in which wetting in the same systems was investigated. Therefore, the contact angles are known for all studied systems. They include cases with total wetting as well as cases with partial wetting. The temperature varies between the triple point and 3 times the critical temperature of the LJTS fluid. For the systems with partial wetting, the adsorption is studied not only up to the saturation pressure but also in the metastable region. For all systems, the surface excess is determined as a function of pressure and temperature. Furthermore, data on the thickness and structure of the adsorbed layers is reported. In some of the systems, prewetting is observed.

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