Charged Drops Don’t Splash

When a droplet falls on a surface, it spreads itself horizontally into a thin lamella. Sometimes — depending on factors like viscosity, impact speed, and air pressure — that drop splashes, breaking up along its edge into myriad smaller droplets. But a new study finds that a small electrical charge is enough to suppress a drop’s splash, as seen below.

The drop’s electrical charge builds up along the drop’s surface, providing an attraction that acts somewhat like surface tension. As a result, charged drops don’t lift off the surface as much and they spread less overall; both factors inhibit splashing.* The effect could increase our control of droplets in ink jet printing, allowing for higher resolution printing. (Image and research credit: F. Yu et al.; via APS News)

*Note that this only works for non-conductive surfaces. If the surface is electrically conductive, the charge simply dissipates, allowing the splash to occur as normal.

#dropletImpact #droplets #electricalField #electrohydrodynamics #fluidDynamics #lamella #physics #science #splashes #splashing

Plasma lighters — as their name indicates — use plasma in place of burning butane. Plasma — our universe’s most common state of matter — is a gas that’s been stripped of its electrons, ionizing it so that it’s electrically and magnetically active. In these lighters (as well as other plasma generators), a high-voltage current jumps between two nodes to ignite the spark. In effect, it’s a tiny lightning bolt you can hold in your hand. (Though I don’t recommend that you try to literally hold it; plasma burns suck.) (Video and image credit: J. Rosenboom; via Nikon Small World in Motion)

https://fyfluiddynamics.com/2024/10/a-plasma-arc-lights/

#combustion #electricalField #fluidDynamics #magnetohydrodynamics #physics #plasma #science

A quartet of mushroom-shaped structures tower nearly 6 meters above the Olympic Village. Known as Aerophiltres, these devices filter particulates out of the air to provide cleaner air for the Village, despite its proximity to major roadways. There’s no need to change out the filters in the Aerophiltres, though, because they don’t have any. Instead, the devices ionize fine particles, encourage them to clump together, and then capture them on highly-charged metal plates. A fan near the base sucks polluted air in through the top and expels clean air at the ground level. According to the engineers, the system is capable of removing 95% of particulates and producing nine Olympic-sized swimming pools’ worth of clean air each hour. Compared to traditional systems — which require lots of power to suck air through filters that get progressively more clogged — the Aerophiltres are energy efficient, highly effective, and easy to maintain. (Image credit: SOLIDEO/C. Badet; via DirectIndustry)

Related topics: How manta rays filter without clogging, making artificial snow, and building whitewater rafting courses

Catch our past and ongoing Olympic coverage here.

https://fyfluiddynamics.com/2024/08/paris-2024-clearing-the-air/

#airPollution #electricalField #filtration #fluidDynamics #olympics #Paris2024 #particulates #physics #science