From “liquid lace” to “Medusa Drop”, researchers compete to obtain the best image of fluid flow

Each year at its annual meeting, the Division of Fluid Dynamics of the American Physical Society sponsors a competition for the best images in various categories, all related to fluid flow.

This year’s gallery was presented at the Division’s 76th meeting in November in Washington, DC, with 12 artistic videos and images selected in four different categories. Here are some of the winners.

‘Liquid lace’

Polymer 3D printers require careful adjustment to wind their material onto a substrate. Laying down too much polymer too slowly can result in creases or coil forming patterns in the wire layout as some of the wire builds up on itself. Stacking on top of an existing kinky coil can cause structural disorder and instability (see video).

Here, a team from Princeton University records the pattern when too little material is printed too slowly. The resulting pattern results in ordered, stable layers, a sort of “lace” with gaps in part of the structure, using less material and making printing faster.

Gaps in the lace can be controlled by layer height and printing speed, which change the density of the final printed structure. Watch the video while listening to Bach’s Violin Sonata No. 2 in A minor.

“Let go of Medusa”

Inducing vibrations in a small drop of weightless liquid creates a surprising pattern of “jets” and “craters” that look a bit like the husk of a chestnut seed.

These researchers, who created this image from digital simulations, compare it to the hair of Medusa, the Greek goddess who transformed spectators into stone. That’s why they call their image the “Drop Medusa” (shown at the beginning of this article).

High amplitude radial vibrations at a regular frequency of 1040 Hertz lead to chaotic, non-linear waves where wave superpositions create the jet and crater effect when the drop bursts.

‘Hydroelastic’

To illustrate the interaction between hydrodynamics and elasticity (“hydroelasticity”), this group photographed objects dropped onto a surface of liquid water. If the object enters the water at sufficient speed, an air cavity forms around it, below the surface.

Usually this cavity has smooth walls, but for some impactors the force of the impact creates vibrations that leave a nest of curious ripples or ripples along the walls of the air cavity. Understanding this interaction could, as the authors write, “have implications for biological divers or naval and aerospace structures.”

Frost propagation dynamics

Water droplets form when moisture comes into contact with a cold surface, called “respiratory patterns.” The droplets merge into larger droplets, with new, smaller droplets forming in the empty spaces between them. In this video, a sudden cooling of the underlying surface shows the droplets freezing and releasing latent heat, observed with an infrared camera.

The droplets freeze from the surface; frost spreads across the surface of water condensation figures by freezing individual droplets and forming ice bridges between them, ending in a charming spike at the top of the frozen droplets. The video here shows some of the beautiful features and movements.

Other gallery entries can be found here. The “Traveling Gallery of Fluid Motion” exhibition, presented by the American Physical Society — Division of Fluid Dynamics, can be viewed as part of the Cultural Program of the National Academy of Sciences (CPNAS) from October 2, 2023 to February 23, 2024 Entitled “Chaosmosis: Assigning Rhythm to the Turbulent,” it is located at 2101 Constitution Ave., NW, Washington, DC, National Academy of Sciences Building, Upstairs Gallery.

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