Schooling at Scale

Relatively simple visual and hydrodynamic signals are enough to make digital fish school in ways that resemble living ones. Here, researchers look at what happens when well-behaved schools of fish get too big. The researchers first demonstrate that their schools behave reasonably at one hundred members, either in a schooling configuration or a group milling around a central region.

At one thousand fish, the schools are still reasonably coherent and sensible. But at fifty thousand fish, the picture is drastically different. Neither schooling nor milling groups are able to remain together. They fracture and scatter into smaller groupings. (Video and image credit: H. Hang et al.)

#2025gofm #activeMatter #biology #collectiveMotion #fish #fluidDynamics #instability #numericalSimulation #physics #schooling #science

Bursting an Oobleck Bubble

When soap bubbles burst, the hole grows as an expanding circle. But not every fluid bursts this same way. Here, researchers let air rise through oobleck–a fluid made from cornstarch suspended in water–to form a bubble. In time, as with all bubbles, the oobleck bubble bursts. But–in keeping with oobleck’s solid-like properties–the film tears open and fractures. As it sinks back into the liquid, it wrinkles before it slowly relaxes back into fluid form. (Video and image credit: X. Zhang et al.)

#2025gofm #bubbles #fluidDynamics #oobleck #physics #science

Bursting Bubbles

When air bubbles rise through a liquid, they scavenge dust, viruses, microplastics, and other impurities as they go. Once at the surface, these contaminant-covered bubbles thin and burst, generating many tiny droplets that arc through the air above. You’re likely familiar with the sight and sensation from a glass of champagne or soda.

Here, researchers have stacked two sets of sequential images to illustrate this complicated flowscape. Under the surface, a trio of photos are stacked to show bubbles rising and gathering at the surface. In the air, the researchers have stacked thirty sequential images, which together trace out the parabolic arcs of droplets sprayed by the bursting bubbles. (Image credit: J. Do and B. Wang)

#2025gofm #bubbles #bursting #droplets #flowVisualization #fluidDynamics #physics #science

Bioconvection

Convection isn’t always driven by temperature. Here, researchers explore the convective patterns formed by Thiovulum bacteria. These bacteria are negatively buoyant, meaning they will sink if they aren’t swimming. They also have an asymmetric moment of inertia, so any flow moving past them tends to affect their swimming direction.

When let loose in a Hele-Shaw cell with a oxygen levels that decrease with depth, the bacteria create complex convection-like patterns. They swim slowly upward in wide, slow plumes and sink in denser, narrow plumes. In other areas, they form large-scale rotating vortices. (Video and image credit: O. Kodio et al.)

#2025gofm #bioconvection #biology #convection #flowVisualization #fluidDynamics #physics #science

Inside Cepheid Variable Stars

Cepheid variable stars pulsate in brightness over regular periods. That’s one reason astronomers use them as a standard candle to judge distances–even for stars well outside our galaxy. In this image, researchers display a simulation of convection inside a Cepheid eight times more massive than our sun. The colors represent vorticity, with zero vorticity in white.(Image credit: M. Stuck and J. Pratt)

#2025gofm #astrophysics #CFD #computationalFluidDynamics #convection #flowVisualization #fluidDynamics #numericalSimulation #physics #science

“Broken Water, Like Broken Glass”

How can you break water? By accelerating it so quickly that the pressure drop forms cavitation bubbles. Here, a steel piston rests against a transparent plate, all underwater. When a hammer strike accelerates the piston away at around 1000g, the severe pressure drop tears the water into bubbles (bottom, left). As the bubbles expand, the nearby piston squishes them into pancakes (bottom, center). As they continue growing, the bubbles press into one another, squeezing thin ridges of water between them. The result (center) resembles broken glass. (Image credit: J. da Silva et al.)

#2025gofm #cavitation #flowVisualization #fluidDynamics #physics #science

A Bubbly Heart

Next time you fill your water bottle, watch closely and see if you can spot a bubble heart like these. When a jet falls into a pool, it pulls air in with it. The low pressure of the jet pulls bubbles inward, even as shear pulls the bubbles downward with the sinking liquid. If the bubbles are large and there’s enough momentum in the jet, the lower portion of the bubble will get pulled into a conical shape, while the upper portion remains a hemisphere. That forms one lobe of the heart. The other half requires a second bubble. But with a little patience and luck, you can form a complete heart. Happy Valentine’s Day! (Image credit: S. Tuley et al.)

#2025gofm #bubbles #fluidDynamics #fluidsAsArt #jets #physics #science #surfaceTension

Jupiter in a Lab

The vivid bands of a gas giant like Jupiter come from the planet’s combination of rotation and convection. It’s possible to create the same effect in a lab by rapidly spinning a tank of water around a central ice core. That’s the physical set-up behind this research poster–note the illustration in the lower right corner. The central snapshots show how temperature gradients on the water surface change the faster the tank rotates. At higher rotational speeds, the parabolic water surface gets ever steeper and Jupiter-like temperature bands form. (Image credit: C. David et al.)

#2025gofm #atmosphericScience #convection #flowVisualization #fluidDynamics #Jupiter #physics #planetaryScience #rotatingFlow #science #turbulence

Flow Through Granular Beds

We often rely on water draining through beds of grains, whether it’s the soil foundation beneath a building or the sand-and-gravel-filter used in water treatment. But how does water move through these tortuous porous passages? That’s what we see in this video, which places grains in a jig resembling an ant farm and lets us watch as water–and air–drain through the grains. The result is more complicated than you might imagine, with dry pockets, weak spots, and developing sinkholes. (Video and image credit: J. Choi et al.)

#2025gofm #drainage #flowVisualization #fluidDynamics #granularMaterial #physics #porousFlow #science

Inside a Bubble’s Burst

When bubbles burst at an interface, both their exterior and interior get spread into the air. Here, researchers watch as a fog-filled bubble rises through silicone oil and settles as the surface. Instabilities ripple down the bubble’s cap as it thins, and, once the bubble bursts, the fog from within is pushed upward, curling into a vortex as it goes. (Video and image credit: R. Shabtay and I. Jacobi; via GFM)

#2025gofm #bubbles #bursting #flowVisualization #fluidDynamics #instability #physics #science #vortex