Nicole SharpJul 30, 2025

Crown Splash

When a falling drop hits a thin layer of water, the impact sends up a thin, crown-shaped splash. This research poster shows a numerical simulation of such a splash in the throes of various instabilities. The crown’s thick edges are undergoing a Rayleigh-Plateau instability, breaking into droplets much the way a dripping faucet does. On the far side, the crown has rapidly expanding holes that pull back and collide. The still-intact liquid sheet at the base of the crown shows some waviness, as well, hinting at a growing instability there. (Image credit: L. Kahouadji et al.)

#2024gofm #CFD #computationFluidDynamics #crownSplash #fluidDynamics #instability #physics #PlateauRayleighInstability #science #splashing

Nicole SharpApr 23, 2025

Drops on the Edge

Drops impacting a dry hydrophilic surface flatten into a film. Drops that impact a wet film throw up a crown-shaped splash. But what happens when a drop hits the edge of a wet surface? That’s the situation explored in this video, where blue-dyed drops interact with a red-dyed film. From every angle, the impact is complex — sending up partial crown splashes, generating capillary waves that shift the contact line, and chaotically mixing the drop and film’s liquids. (Video and image credit: A. Sauret et al.)

#2024gofm #crownSplash #dropletImpact #droplets #flowVisualization #fluidDynamics #fluidsAsArt #physics #science #wetting

Nicole SharpJul 12, 2024

Since Harold Edgerton’s experiments with stroboscopic photographs in the 1930s, we’ve been fascinated by the shape of splashes. These days students and artists can take advantage of programmable external flashes to capture this split-second moment of impact. Here, a pink-dyed drop of ethanol strikes a jet rising from a pool of glycerin, milk, and food coloring. The resulting splash is umbrella-like, with a thickened rim that shows tiny ligaments of fluid — an early sign of the instability that will ultimately detach droplets from the splash. This image was taken by students in a course that connects art and fluid mechanics. (Image credit: L. Sharpe et al.; via Physics Today)

https://fyfluiddynamics.com/2024/07/making-a-splash/

#crownSplash #fluidDynamics #fluidsAsArt #instability #physics #science #splashes #WorthingtonJet

Milk Drop Coronet | MIT Museum

Considered one of the most important photographs of all time, Harold Edgerton saw this particular image (taken January 10, 1957) as just one of many in his life-long quest for the perfect coronet. For example, he took a similar image in 1937 in black and white which would be published in his first book "Flash" in 1939. Edgerton's lab notebook entry for that day describes the details of how he conceptualized this particular image. Edgerton's son Robert described the creation of this image this way: "A beam of light and a photocell was used in both examples to trigger the flash after an adjustable electronic delay. A dropper produces a small drop following the main drop of liquid from the neck pinching off in two places. This small drop following the main drop is seen in the photograph of the splash made by the main drop. The drop of milk is splashing into the thin film of milk that has formed on the surface from the previous drop of milk. The shape of the coronet is very dependent on the thickness of the film of milk, the size of the drop, and the height through which the drop has fallen. Milk was selected as the liquid because it is white and translucent and attractive to photograph. Photographing splashes has a long history in particular see Worthington's book on that subject using sparks as a light source and using two drops, one as part of an electrical switching arrangement to achieve the timing. My father's contribution was his development of the electronic flash technology so that it had enough intensity for color photography and still have a short enough exposure time to have a crisp image of the moving milk droplets. He also devised the triggering scheme and delay used to capture this critical moment in the evolving shape of the splash."

MIT Museum