At first glance, an old jacuzzi full of sand isn't all that interesting, unless your goal is to create a miniature beach or the world's most extravagant cat bath. But if you inject enough air pressure into the system, the sand changes its behavior completely, and starts to resemble water. What exactly is happening? Mark Rober's latest video explains it wonderfully and also shares some details for building your own fluidized sand bed.
Anakin Skywalker once declared that he doesn't like sand because it's "rough, coarse, irritating, and it gets everywhere". These technical observations within a supposedly romantic scene confirmed (once again) that George Lucas should have stepped aside, but I think Anakin would be delighted to see this: sand behaving like water. All we need is air and a good distribution system for the pressure. Most likely any DIY attempt will require several prototypes, but it's definitely within our reach, and Mark Rober's latest video (the same one about the grenades and the carnival games) is excellent proof of that:
The Fluidization Process
Why does the sand change so radically? The process is called fluidization. An upward current of fluid (it also works with liquids, not just gases) generates a suspension of particles, causing the solid phase to behave like a liquid. The idea is to balance the system so that air pressure "cancels out" the force of gravity to a certain extent. If there isn't enough pressure, the effect will be very limited, while excess pressure will send sand flying in all directions. The tank of an average compact compressor will only provide a few seconds of activity in a fluidized bed, so perhaps it's best to rent a nitrogen cylinder.
Honestly, I can't share any data on the cost of building a fluidized bed (prices vary a lot from region to region), but I imagine a small-scale version shouldn't hit the wallet too hard, as long as we already have access to a compressor.
