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

A so-called cross-correlation for two consecutive images will give you the direction and value of the flow velocity in the recorded flow field.

Here's an example where I recorded the water movement surrounding a bubble rising through the field of view
2/2

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RT @drlutzboehm
So, I told you about the #bubble and #CFD (see 🧵). A couple of years later I used the LASER-based technique #ParticleImageVelocimetry #PIV to investigate the flow…
https://twitter.com/DrLutzBoehm/status/1454076234619629574