2013 Virtual Pressroom

Excited Sessile Drops Dance Harmonically

Chun-Ti Chang, Susan Daniel, Paul H. Steen
Cornell University

By imaging mechanically oscillated sessile drops at high speed, 37 mode shapes are observed. To visualize the shapes, we place mesh under the drop, project light from below, and read off the shapes from the deformation of the mesh from top view. The mode shapes are first identified by their numbers of layers and sectors and then related to spherical harmonics.

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Air Bubbles "Catching Up" in Viscous Media

Sharad Chand Ravinuthala, Ismail Celik
West Virginia University

This set of videos shows the causes and effects of air bubbles rising in continuous media. It is interesting to observe that rising bubbles (in the case of viscous media like corn oil) get caught in each other’s wake and thus accelerate to meet their coalescence partner. A lesser viscous medium like water results in smaller bubble sizes and arguably better mixing.

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Star Drop Oscillations

Weiyu Ran, Steven Fredericks, John R. Saylor
Clemson University

This video shows a liquid drop levitated in an ultrasonic standing wave field. Once levitated the drop was flattened into a disk shape by increasing the ultrasonic field strength. This flattened drop was then excited to create star drop patterns by exciting the drop at its resonance frequency. Different oscillatory modes were induced by varying the frequency at which the field strength was modulated.

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Dancing Droplets

Nate Cira, Manu Prakash
Stanford University

We have characterized the beautiful and highly dynamic behavior of two component droplets on clean, high-energy surfaces. We use what we discovered to create devices.

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Fast and Scalded

Alvaro Marin
Bundeswehr Univ. Munich, Germany

Daniel del Cerro, Gert W. Romer, Detlef Lohse
Univ. of Twente, Netherlands

Leidenfrost droplets can be easily seen in your own kitchen when sprinkling some water drops on a hot pan. These droplets will hover around the pan, being levitated by their own vapor. However, when the surface is properly micro-mechanized, we can make the droplets to hover in the direction we want, and at surprisingly high speeds.

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Elastic Swimmer on a Free Surface

Sophie Ramananarivo, Benjamin Thiria, Ramiro Godoy-Diana
Physique et Mécanique des Milieux Hétérogènes, Ecole Supérieure de Physique et de Chimie Industrielles

We present in this fluid dynamics video a novel experimental setup with self-propelled swimmers on a free surface. The swimmers, modeled as flexible thin filaments, are subjected to external electromagnetic forcing driving a propagating elastic wave that gives rise to self-propulsion.

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Dynamics of Jumping Water Droplets

Nenad Miljkovic, Daniel Preston
Massachusetts Institute of Technology

Ryan Enright
Bell Labs Ireland

Alexander Limia, Evelyn Wang
Massachusetts Institute of Technology

This video shows the different interaction mechanisms of coalescence-induced droplet jumping during condensation on a nanostructured superhydrophobic surface. High-speed imaging was used to show jumping behavior on superhydrophobic copper oxide and carbon nanotube surfaces. Videos demonstrating multi-jumping droplets, jumping droplet return to the surface, and droplet-droplet electrostatic repulsions are shown.

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Physics of Urine

Patricia Yang, Jonathan Pham, Jerome Choo, David Hu
Georgia Institute of Technology

Intermediate and large mammals expel their urine by jet, including dog, goat, cow and elephant, over nearly constant duration from 10 to 30 seconds. Small mammals such as rats produce drops because of viscosity and surface tension.

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Catastrophic Cracking Courtesy of Quiescent Cavitation

D. Jesse Daily, Ken Langley, Scott L. Thomson, Tadd T. Truscott
Brigham Young University

A popular party trick is to fill a glass bottle with water and hit the top of the bottle with an open hand, causing the bottom of the bottle to break open. We investigate the source of the catastrophic cracking through the use of high-speed video and an accelerometer. Upon closer inspection, it is obvious that the acceleration caused by hitting the top of the bottle is followed by the formation of bubbles near the bottom. Moments later, the cavitation bubbles collapse at roughly 10 times the speed of formation, causing the bottle to break.

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Patient-Specific Heart Flow Simulations

CHNAFA, Christophe, MENDEZ Simon, NICOUD Franck
University Montpellier II, FRANCE

Numerical simulations of the blood flow in a realistic left heart were performed. The left heart geometry is extracted from medical images, and the endocardium movements are reconstructed by image registration. Numerical simulation is a powerful tool to study this complex, intermittent flow.

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Underwater Gas Expansion and Deflagration

Van Jones, Kariann Vander Pol, John Gilbert, Leigh McCue-Weil
Virginia Tech

This video shows the underwater combustion of a propane-air mixture in an acrylic cylinder. The combusting gasses expand to form a bubble, which then collapses forming a pair of jets. The experiment is designed to provide visual data and pressure time-histories for future CFD validation studies.

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Supercooled Droplet or Ice?

Carlo Antonini, Adrian Mularczyk, Tanmoy Maitra, Manish K. Tiwari, Dimos Poulikakos
Laboratory of Thermodynamics in Emerging Technologies, ETH Zurich, Switzerland

In this fluid dynamics video, we show the trick played by a supercooled liquid water droplet against a superhydrophobic surface. The water drop shows a dual personality, impacting onto the surface the first time while still in the liquid state and then re-impacting as a frozen ice crystal.

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A Fluid that Juggles

Enrique Soto, Roberto Zenit
Universidad Nacional Autonoma de Mexico

In this video we show how a slightly inclined jet of water can hold a light ball in a steady position. The jet is able to juggle the ball. This is a good example of Bernoulli's principle (the fluid accelerates around the ball, creating a low pressure stable region). The interaction of the water and the ball also produce interesting shapes of streams, jets, films and filaments that are continously forming and breaking.

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