Showing papers on "Laplace pressure published in 2005"
TL;DR: In this article, a new surface tension force formulation for a diffuse-interface model is derived for incompressible, immiscible Navier-Stokes equations separated by free interfaces.
246 citations
TL;DR: Experimental results indicate that evaporation of the last thin layer of water is significantly slower than the rest of the drop, which can be due to surface forces.
Abstract: The evaporation of water drops with radii ∼20 μm was investigated experimentally by depositing them onto atomic force microscope (AFM) cantilevers and measuring the deflection versus time Because of the surface tension of the liquid, the Laplace pressure inside the drop, and the change of interfacial stress at the solid−liquid interface, the cantilever is deflected by typically a few hundred nanometers The experimental results are in accordance with an analytic theory developed The evaporation process could be monitored with high accuracy even at the last stage of evaporation because (1) cantilever deflections can be measured with nanometer resolution and (2) the time resolution, given by the inverse of the resonance frequency of the cantilever of ∼03 ms, is much faster than the typical evaporation time of 1 s Experimental results indicate that evaporation of the last thin layer of water is significantly slower than the rest of the drop, which can be due to surface forces This drop-on-cantilever sys
73 citations
TL;DR: In this article, the effect of mass transfer and surface expansion on the final droplet size in membrane emulsification has been investigated using a finite element program called the surface evolver, which allows the user to track the droplet shape as it grows.
61 citations
TL;DR: In this article, the dependence of foam rheology on the nature of its components (gas, liquid and surfactant) was investigated, and it was shown that the elastic modulus G �, once normalized by the Laplace pressure, does not depend on the foam components.
59 citations
TL;DR: In this paper, a simple picture of transient and stationary transport in lipid nanotubes connecting two vesicles is given, when a difference of membrane tension is imposed at time t = 0, either by pressing one vesicle with a micro-fiber, or by adding a surplus of membrane lipid.
Abstract: We give a simple picture of transient and stationary transport in lipid nanotubes connecting two vesicles, when a difference of membrane tension is imposed at time t = 0, either by pressing one vesicle with a micro-fiber, or by adding a surplus of membrane lipid. The net result is a transport of membrane from the tense towards the floppy vesicle. In the early stage, the tube remains cylindrical, and the gradient of surface tension gives rise to two opposite flows of the internal liquid: a Marangoni flow towards the direction of high tension, and a Poiseuille flow (induced by Laplace pressures) in the opposite direction. At longer time, the tube reaches a stationary state, where curvature and Laplace pressure are balanced. Marangoni flows dominate for giant vesicles, where Laplace pressure is negligible.
49 citations
TL;DR: In this article, a theory of the spontaneous formation of spatially regular hexagonal arrays of nanopores in aluminum oxide film growing during aluminum anodization is presented, which is caused by a positive feedback between the oxidation-dissolution rates and variations of electric field caused by perturbations of the metal-oxide and oxide-electrolyte interfaces.
Abstract: A theory of the spontaneous formation of spatially regular hexagonal arrays of nanopores in aluminum oxide film growing during aluminum anodization is presented. Linear stability analysis shows that, in certain ranges of the applied voltage and electrolyte pH, the oxide film is unstable with respect to perturbations with a well-defined wavelength. The instability is caused by a positive feedback between the oxidation-dissolution rates and variations of electric field caused by perturbations of the metal-oxide and oxide-electrolyte interfaces. The competition between this instability and the stabilizing effects of the Laplace pressure and elastic stress provides the wavelength selection mechanism. The hexagonal ordering of pores results from the resonant quadratic nonlinear interaction of unstable modes.
35 citations
TL;DR: In this paper, a model of sintering for materials with bimodal pore distribution is formulated as a generalization of the continuum isotropic theory of Sintering.
Abstract: A model of sintering for materials with bimodal pore distribution is formulated as a generalization of the continuum isotropic theory of sintering. In contrast to known models that only contain one behavioral parameter, i.e. porosity, the model suggested is described by two parameters for each type of pore. The evolution equations for each type of pore as well as the effective viscosity coefficients and Laplace pressure (sintering potential) are determined by unit cell analysis.
12 citations
01 Aug 2005-Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems
TL;DR: In this paper, the dynamics of a liquid meniscus bridge between solid surfaces were analyzed based on the continuum lubrication theory assuming a small vibration of the spacing, and the geometry of the maniscus was considered.
Abstract: The dynamics of a liquid meniscus bridge between solid surfaces were analyzed based on the continuum lubrication theory assuming a small vibration of the spacing. The geometry of the meniscus considered in this study was the finite meniscus ring. The following two meniscus models were considered: (1) the fixed boundary position of the meniscus and variable contact angle (VCA) model and (2) the fixed contact angle and variable boundary position (VBP) model. The time-dependent Reynolds equation was solved under the boundary condition considering the Laplace pressure, assuming that the mass of the liquid in the meniscus is conserved. It was found by linearization that the pressures and the load-carrying capacities of both models have three terms, i.e., a time-dependent squeeze term due to the viscosity of the liquid, a spring term due to the dynamic Laplace pressure and a static meniscus force term. The comparisons between these models and experimental results were also presented.
11 citations
TL;DR: In this paper, the dynamics of positronium bubble growth and dissipative energy loss accompanying this process were considered in the hydrodynamic approximation for liquid media with strongly differing values of the surface tension and viscosity.
Abstract: The dynamics of positronium bubble growth and dissipative energy loss accompanying this process were considered in the hydrodynamic approximation for liquid media with strongly differing values of the surface tension and viscosity. The driving force of the growth of the positronium bubble is repulsive exchange interaction between the electron inherent in the positronium atom and electrons of surrounding molecules. Intermolecular attraction (Laplace pressure) and viscous media retard bubble growth. In liquid helium and glycerol, the Ps formation time is comparable to or even longer than the parapositronium lifetime. Dissipative energy losses accompanying the bubble growth are substantially higher than the surface energy of the equilibrium bubble.
9 citations
TL;DR: It is shown that oscillatory adhesion forces and internal forces in nanoporous adsorbents have a common thermodynamic origin and can be discussed in the framework of adsorption compression mechanisms.
8 citations
01 Aug 2005-Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems
TL;DR: In this article, the formation of molecularly thin liquid bridges between solid surfaces having molecular-scale roughness was simulated by using the molecular dynamics, and the projected profiles were able to be approximated by arcs.
Abstract: By using the molecular dynamics, formation of molecularly thin liquid bridge between solid surfaces having molecular-scale roughness was simulated. Upon comparing the projected profiles of liquid bridges between solid surfaces with different roughness, it was found that the layered molecular arrangement inside the liquid bridge was disturbed by the molecular-scale roughness on the surfaces and the projected profiles were able to be approximated by arcs.
TL;DR: It is argued and demonstrated that techniques which have low resolutions such as microscopy will measure quite different kinetics: at short times a power of 14 as for wetting liquids and then a sudden equilibration as reported in these experiments.
Abstract: Kinetics of wetting by a polymer solution have been studied theoretically for a film pinned to a slot. The fluid mechanical equations have been solved using a numerical scheme. The role of polymers appears in the disjoining pressure in the model. The spreading kinetics are observed to follow a power law: a power of 14 is observed at short times due to the Laplace pressure, and 12 at large times under the Hamaker part of the disjoining pressure at very large times and with no equilibration. It is argued and demonstrated that techniques which have low resolutions such as microscopy will measure quite different kinetics: at short times a power of 14 as for wetting liquids and then a sudden equilibration as reported in these experiments. It is also argued on the basis of steric exclusion, and quantified in the disjoining pressure, that the behavior returns to that of wetting liquids when the polymer molecular weight becomes very high, as also observed in the experiments. Examples of how these features can fin...
01 Jan 2005
TL;DR: In this article, it was shown that the surface tension of the liquid on which the organic molecules spread is more than 100 times greater than the osmotic pressure theory, and that the area available for one molecule is impossibly small for a dibromophenol.
Abstract: When crystals of camphor or another suitable organic compound are placed on the surface of water, surface tension of the latter is lowered from the value (Y0) characteristic for water to a value (ye) characteristic for the organic substance. The difference Y0 Ye was termed "equilibrium surface pressure" and was supposed to be analogous to the equilibrium vapor pressure of the crystals. I f this hypothesis were correct, the value of 7 o 7e would have been independent of the liquid on which crystals spread. I t was found, however, tha t Y0 7e on mercury was much greater than on water (1). The absolute value of Y0 7e is too large for either the above-mentioned hypothesis or the related notion which makes Y0 ye equal to the two-dimensional osmotic pressure. For at least one organic substance (2.4-dinitrophenol) it was above 100 g/see 2. I f this value is inserted in the equation for the osmotic pressure of ideal two-dimensional solutions, the area available for one molecule turns out to be less than 4/~2, i. e., impossibly small for a dibromophenol; the corresponding area for several other molecules was about 7 A 2, that is also too small. Furthermore, spreading pressure of a small amount (corresponding to area per molecule equal to 810 A 2) of ethyl palmitate on mercury was determined (ref. 2, p. 34) and found to be more than 100 times as great as the osmotic pressure theory predicts. Therefore, another theory of the effect was proposed (1), namely tha t surface tension of the liquid pulls molecules out of the crystal until the reduced surface tension becomes too small to overcome the cohesion (~) of the solid (i. e., becomes equal to the "equilibrium surface tension" 7e). I f ~ is the thickness of the surface layer of the liquid, approximately ~e = ~ ~3. [1]