Surface tension

About: Surface tension is a research topic. Over the lifetime, 25410 publications have been published within this topic receiving 695471 citations.

Dimensional limitations of silicon nanolines resulting from pattern distortion due to surface tension of rinse water

Abstract: In a nanometer‐scale regime, high‐aspect‐ratio Si lines running in parallel bend plastically toward each other during the drying process after being rinsed in water. Pattern distortion occurs when the line distance is smaller than the product of the squared aspect ratio and a constant k dependent on the condition of the Si surface, i.e., (distance)

Viscoelastic properties of oxide-coated liquid metals

Abstract: Many liquid metals exposed to air develop an oxide film on their outer surface. This film is sufficiently solid-like to provide mechanical stability to small liquid metal droplets, yet weak enough to allow the droplets to be malleable. These properties are useful in both micro-electronics and microfluidics; however, little is known about how to characterize them. Here we probe the elastic, yielding, and relaxation properties of oxide-coated gallium and eutectic gallium indium using a rheometer equipped with a parallel-plate geometry. By using parallel plates of different size, we show that surface stresses dominate bulk stresses. These experiments also demonstrate that the apparent elastic properties of the oxide film are highly sensitive to its strain history. Moreover, the apparent elasticity is sensitive to the stresses stored in the oxide skin. We probe these stresses and their time-dependence, with both torque and normal force measurements. We also characterize the time-dependence of the elasticity b...

Almost Exponential Decay of Periodic Viscous Surface Waves without Surface Tension

Abstract: We consider a viscous fluid of finite depth below the air, occupying a three-dimensional domain bounded below by a fixed solid boundary and above by a free moving boundary. The fluid dynamics are governed by the gravity-driven incompressible Navier–Stokes equations, and the effect of surface tension is neglected on the free surface. The long time behavior of solutions near equilibrium has been an intriguing question since the work of Beale (Commun Pure Appl Math 34(3):359–392, 1981). This paper is the third in a series of three (Guo in Local well-posedness of the viscous surface wave problem without surface tension, Anal PDE 2012, to appear; in Decay of viscous surface waves without surface tension in horizontally infinite domains, Preprint, 2011) that answers this question. Here we consider the case in which the free interface is horizontally periodic; we prove that the problem is globally well-posed and that solutions decay to equilibrium at an almost exponential rate. In particular, the free interface decays to a flat surface. Our framework contains several novel techniques, which include: (1) a priori estimates that utilize a “geometric” reformulation of the equations; (2) a two-tier energy method that couples the boundedness of high-order energy to the decay of low-order energy, the latter of which is necessary to balance out the growth of the highest derivatives of the free interface; (3) a localization procedure that is compatible with the energy method and allows for curved lower surface geometry. Our decay estimates lead to the construction of global-in-time solutions to the surface wave problem.

A Theoretical Study of Instabilities at the Advancing Front of Thermally Driven Coating Films

Abstract: A thin liquid coating can spread vertically beyond the equilibrium meniscus position by the application of a temperature gradient to the adjacent substrate. So called super-meniscus films experience a surface shear stress which drives flow toward regions of higher surface tension located at the cooler end of the substrate. The Marangoni stresses responsible for this spreading process can also be used to coat horizontal surfaces rapidly and efficiently. Experiments in the literature have shown that in either geometry, the advancing front can develop a pronounced ridge with lateral undulations that develop into long slender rivulets. These rivulets, which prevent complete surface coverage, display a remarkable regularity in height, width, and spacing which suggests the presence of a hydrodynamic instability. We have performed a linear stability analysis of such thermally driven films to determine the most dangerous wavenumber. Our numerical solutions indicate the presence of an instability at the advancing front of films which develop a sufficiently thick capillary ridge. Our results for the film thickness profiles and spreading velocities, as well as the wavenumber corresponding to the most unstable mode, compare favorably with recent experimental measurements. An energy analysis of the perturbed flow reveals that the increased mobility in the thickened portions of the films strongly promotes unstable flow, in analogy with other coating processes using gravitational or centrifugal forces. Copyright 1997Academic Press

The surface tension of liquid pure aluminium and aluminium−magnesium alloy

Abstract: This paper discusses the results of several experiments designed to further illustrate the recent findings of the present authors according to which, if a virtually leak-fee maximum bubble pressure system is used to measure the surface tension of liquid aluminium, a surface tension around 1100 mJ m−2 is first obtained, decreasing to the oxidized value (around 865 mJ m−2) as the experiment proceeds and oxygen enters the system mainly through the capillary walls. The peculiarities and difficulties inherent to the maximum bubble pressure method are illustrated. For instance, a study of the time needed for the surface tension to decrease to the oxidized value as a function of temperature reveals the important role played by the vapour pressure in the process. This is further illustrated by considering Al-Mg alloys, as magnesium has a different heat of vaporization and a much larger vapour pressure than aluminium at the measuring temperatures. Results for the changes in density and surface tension for the oxidized and unoxidized cases induced by magnesium (up to 8 wt%) are also presented and compared to previous data.