Understanding Schlieren

Schlieren techniques are one of my favorite forms of flow visualization. They cleverly make the invisible visible through an optical set-up that’s sensitive to changes in density. They’re great–as seen in the examples here–for seeing local buoyant flows like the plumes that rise from a candle, or for making gases like carbon dioxide visible. They’re also excellent for visualizing shock waves.

In this video, physicist David Jackson explains how one particular flavor of schlieren–one using a spherical mirror–works. There are lots of other possible schlieren set-ups, too, though each one has its quirks. (Video and image credit: All Things Physics; submitted by David J.)

Connecting Canals

Before the rise of railroads, canals provided critical commercial shipping infrastructure for many locations worldwide. But connecting canals at different elevations required locks–sometimes a whole series of them–as in the case of Scotland’s Union Canal and the Forth and Clyde Canal. In the canals’ heyday, navigating the 11 locks between them took the better part of a day–one of many reasons that canals fell out of use over time.

When Scotland decided to reconnect the canals in the 1990s, they picked a very different solution for this elevation challenge: the Falkirk Wheel. Grady walks us through the clever engineering of this impressive piece of infrastructure in this Practical Engineering video. (Video and image credit: Practical Engineering)

Particles Deviate From Fluid Flow, Challenging Established Models

Research shows small particles in fluids don't always follow flow paths. This affects environmental cleanup and agriculture. Learn what changes for you.

#ParticleFlow, #FluidDynamics, #EnvironmentalScience, #Research, #ScienceNews

https://newsletter.tf/small-particles-move-differently-than-fluid-flow-new-study/

New research finds tiny particles in liquids move in unexpected ways, unlike what scientists thought. This is important for cleaning up pollution and growing food.

#ParticleFlow, #FluidDynamics, #EnvironmentalScience, #Research, #ScienceNews

https://newsletter.tf/small-particles-move-differently-than-fluid-flow-new-study/

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)

A new study shows how “riding along” with a fluid changes the view: the flow can seem still, waves appear, and even fluid between two sliding plates (Couette flow) stays stable.

Insights for understanding turbulence!

🔗 https://journals.aps.org/prfluids/abstract/10.1103/q2fw-vgrr

#FluidDynamics #Turbulence #LagrangianView #FlowStability #Waves

- Capillarity and viscosity: how liquids move -

Understand the relationship between capillarity and viscosity and their role in droplet dynamics with this video from the "Dynamics of fluid interfaces" MOOC by ESPCI Paris - PSL.

🎥 https://www.youtube.com/watch?v=Mq1EUe3cOCY&list=PLcbz7zf4dTyk9BqlBPLpgI48i9TiorpEi&index=13

#Capillarity #Viscosity #FluidPhysics #FluidDynamics

Sprites and ELVES

Although we are most familiar with the white, branching lightning caused by electrical discharge between clouds and the ground, there are many types of lightning. This fortuitous image captures two: tentacled red sprites and ring-like ELVES. Sprites extend upward from the top of a thunderstorm, in a large but weak flash that lasts only seconds. ELVES appear as a rapidly-expanding disc, thought to be caused by an energetic electromagnetic pulse moving into the ionosphere. They were first discovered in footage from a 1992 Space Shuttle mission. (Image credit: V. Binotto; via APOD)

“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.)

Mars’ young volcanoes show multi-phase magma flows, revealing complex #FluidDynamics beneath Pavonis Mons.
Studying these planetary flows can inform models of heat and phase transfer in extreme environments.

🔗 https://phys.org/news/2026-02-mars-young-volcanoes-complex-scientists.html

#PlanetaryScience #Volcanology #HeatTransfer #MarsResearch