Bulletin of the American Physical Society
64th Annual Meeting of the APS Division of Fluid Dynamics
Volume 56, Number 18
Sunday–Tuesday, November 20–22, 2011; Baltimore, Maryland
Session S26: Surface Tension IV |
Hide Abstracts |
Chair: Jason Tiffany, Johns Hopkins University Applied Physics Laboratory Room: 329 |
Tuesday, November 22, 2011 3:05PM - 3:18PM |
S26.00001: Immersed parallel plates: from repulsion to attraction Paul Concus This mathematical study concerns the behavior of parallel vertical plates of infinite extent and of possibly differing materials dipped into an infinite liquid reservoir. For this classical problem varying modes of behavior can occur, depending on plate separation and contact angles. Under specific conditions the plates will repel each other when sufficiently far apart, with change to large attraction, which can be abrupt, when they are moved closer together. As separation is decreased to a critical value, the liquid/vapor interfaces pass through a family tending to a certain, explicitly known interface yielding zero force. For the initial stages of this procedure computational results depict a striking behavior, that the interfaces in the sequence can actually move away from the limiting interface, not toward it. [Preview Abstract] |
Tuesday, November 22, 2011 3:18PM - 3:31PM |
S26.00002: Direct Observation of Hierarchical Contact Line Depinning Adam Paxson, Kripa Varanasi We report a technique for observing the dynamic behavior of a liquid contact line at high magnification using environmental scanning electron microscopy. We find that on a superhydrophobic surface consisting of an array micropillars, the receding contact line exhibits discrete hierarchical de-pinning events. As the macroscopic contact line recedes across the pillars, a capillary bridge is formed and displays a local microscopic contact angle that is equivalent to the macroscale contact angle observed on a flat surface of the same composition. By considering the line density of the microscale features and the pinning strength of each of those features, we relate the macroscopic contact angle and adhesion to the multiscale hierarchical roughness. This mechanism helps to explain the necessity for multiple length scales exhibited by lotus leaves and other superhydrophobic surfaces. [Preview Abstract] |
Tuesday, November 22, 2011 3:31PM - 3:44PM |
S26.00003: Large Scale Dynamics and Partial Coalescence of Soap Bubbles David Martin, Francois Blanchette We present simulations of the large scale dynamics of soap films. Our model uses a thin, axisymmetric interface, with finite thickness and mass. The interface is treated as a two dimensional front, and we track the local thickness and surfactant concentration. We present results on the coalescence of soap bubbles of different sizes. Conditions are found under which this coalescence is only partial. [Preview Abstract] |
Tuesday, November 22, 2011 3:44PM - 3:57PM |
S26.00004: ABSTRACT MOVED TO L20.00005 |
Tuesday, November 22, 2011 3:57PM - 4:10PM |
S26.00005: Finite Bond number effects in the dripping nozzle Suhwan Choi, Thomas Ward The pressure-drop in a dripping nozzle generated by hydrostatic pressure and surface tension is studied by both theory and experiments. As the hydrostatic pressure is varied in each experiment, the measured pressure-drop can change sign depending on a inner tip diameter, Bond number, angle of valve, and viscosity. The viscous fluids used in the experiments are glycerol-water mixtures with viscosities ranging from 0.176 to 1.09 Pa s and silicone oil having a viscosity of 0.418 Pa s and higher Bond number compared with the mixtures. The pendant drop growth is taken by CCD camera to make observations. The images are examined for the radius of the drop as a function of time and compared with the derived momentum equation which include Bond number effects. We propose a process to use the analysis for estimating the surface tension without the need to measure the interface curvature. [Preview Abstract] |
Tuesday, November 22, 2011 4:10PM - 4:23PM |
S26.00006: Capillary rise in cellulose sponges Jungchul Kim, Ho-Young Kim, L. Mahadevan A cellulose sponge, commonly used for clean-up jobs, can absorb and hold a significant amount of water within its pores, whose size ranges from micrometers to millimeters. We investigate the dynamics of capillary rise of water in the sponge using a combination of experiment and theory. We find that the rate of the capillary rise is significantly lower than Washburn's rule that assumes the sponge as a row of adjoined pores and the liquid flow to be driven by the Laplace pressure. We introduce a novel theory to model the flow in the hygroscopic porous media by combining Darcy's law based on the moisture concentration and the modified Young-Laplace equation. The scaling law constructed through this work agrees well with the experimental results. [Preview Abstract] |
Tuesday, November 22, 2011 4:23PM - 4:36PM |
S26.00007: Coupling between meniscus dynamics and corner flow near a junction Lingguo Du, Hugues Bodiguel, Annie Colin The movement of a liquid-liquid meniscus in a circular tube at small capillary numbers is a rather simple problem since it follows Poiseuille's law with an effective pressure that incorporates the capillary pressure. However, for a tube of arbitrary cross-section exhibiting sharp corners, capillarity requires that the wetting liquid remains along the corners. These corner films may flow. In this work we experimentally investigate the role of these corner flows on the dynamics of a liquid-liquid meniscus, in total wetting conditions, by taking advantage of a microfluidic PDMS cross-junction. Our results show that there is a strong coupling between the corner flows and the displacement of meniscus, when it lies in the vicinity of the junction (up to 10 times the channel width 50$\mu m$). Part of the observations is accounted for by a model based on a network of adaptive hydrodynamic resistances. However, when the size of the corner film is high, a more detailed description of the interface shape is required to account for the observations. [Preview Abstract] |
Tuesday, November 22, 2011 4:36PM - 4:49PM |
S26.00008: Microliquid prism actuated by electrowetting Duck-Gyu Lee, Jaebum Park, Ho-Young Kim A microliquid prism is a microchannel filled with two immiscible liquids whose interface acts as a refractive surface. To steer a beam to construct optical images, the interface profile or the contact angle is modulated through electrowetting. The effective actuation of the liquid prism critically depends on the understanding of liquid flows around the moving interface. We visualize the flow field near the moving contact line formed by water, silicone oil and a glass microchannel using PIV (particle image velocimetry). The flow, which is believed to be visualized for the first time to the authors' knowledge, is clearly distinguished from that in the classical microliquid slugs in that the fluid motion near the electrowetting-driven contact line is localized in the vicinity of the contact line. We also provide a theoretical model to predict the temporal evolution of the interface profile as a function of the liquid properties and the dependency of the contact angle on voltage. [Preview Abstract] |
Tuesday, November 22, 2011 4:49PM - 5:02PM |
S26.00009: Dynamic surface tension effects from molecular dynamics simulations Alex Lukyanov, Alexei Likhtman We will present results of our recent large scale molecular dynamics simulations of dynamic surface tension behaviour in the case of a liquid-gas interface. We will demonstrate the mechanism of surface tension relaxation from a non-equilibrium state in several representative cases: long-chain flexible molecules with Lennard-Jones beads connected by FENE springs and binary Lennard-Jones mixtures (Kob-Andersen model). The methodology of the surface tension evaluation has been successfully tested against the Laplace law in all the cases. [Preview Abstract] |
Tuesday, November 22, 2011 5:02PM - 5:15PM |
S26.00010: Temperature sensitivity of surface tension-driven flows: Application to time-temperature integration John Thomas, Lawrence Hunter, Michael Boyle The effects of time-dependent temperature fluctuations on surface-tension driven fluid flow inside a capillary are modeled using classical hydrodynamics. To begin, we use Newton's second law to derive a non-dimensional equation of motion that describes capillary flow as a function of system geometry, fluid properties, and fluid temperature. We use this model to examine how temperature excursions affect the instantaneous and long-term position and velocity of the fluid front inside the capillary. Next, we examine the combined effects of orientation change and temperature change on fluid movement through the capillary. Using this data, we show how to design a non-powered time-temperature integration device for recording the cumulative temperature exposure history of an asset or local environment. By selecting an appropriate fluid and capillary geometry, we show how such devices can be designed to exhibit arbitrary temperature sensitivities, operate over arbitrary monitoring periods (months to decades), and operate in a manner that does not depend on orientation. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700