Circulation in a Capillary Network

Today’s video shows red blood cells flowing through a capillary network in a rat’s skeletal muscle. At this resolution, our eyes can follow the paths of individual red blood cells squeezing through each capillary, as well as the faster blur of thicker capillaries where many cells can pass at once. Watching videos like this is a great way to build intuition for particle image velocimetry, streaklines, and other flow visualization methods as our brains can readily recognize where the cells are moving fast and where they are slower. (Video and image credit: Dr. G. McEvoy et al.; via Colossal)

https://www.youtube.com/watch?v=dO8P9Qzhv2s&pp=0gcJCfYJAYcqIYzv

#biology #bloodFlow #flowVisualization #fluidDynamics #particleImageVelocimetry #physics #PIV #science

Biodegradable PIV Particles

Particle image velocimetry–PIV, for short–is used to visualize fluid flows. The technique introduces small, neutrally-buoyant particles into the flow and illuminates them with laser light. By comparing images of the illuminated particles, computer algorithms can work out the velocity (and other variables) of a flow. Typical methods use hollow glass spheres or polystyrene beads as the particles that follow the flow, but these options have many downsides. They’re expensive–as much as $200/pound–and they can potentially harm test subjects, like animals whose swimming researchers are studying. Instead, researchers are now looking at biodegradable options for PIV particles.

One study found that corn and arrowroot starches were good candidates, at least for applications using artificial seawater. The powders were close to neutrally-buoyant, had uniform particle sizes, and accurately captured the flow around an airfoil, live brine shrimp, and free-swimming moon jellyfish. (Image credit: M. Kovalets; research credit: Y. Su et al.; via Ars Technica)

#biology #flowVisualization #fluidDynamics #particleImageVelocimetry #physics #PIV #science

And this is basically how you can make experimental #fluiddynamics measurements such as #ParticleImageVelocimetry #PIV in fixed bed reactors used, e.g., as heterogenous catalytic reactors in the chemical industry.

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RT @TheSpaceGal
Using the refractive index to make pennies float 🪄

Impt safety note: dry water beads grow 100x their size (to what you see here), so be extra vigilant with the dry beads before they’ve grown around kids…
https://twitter.com/TheSpaceGal/status/1630628058519719937