[Little Demos] 02 – Home Made Laminar Flow

One of my oldest physics party tricks, now photographed in makeshift home studio.

Safety Advisory: Some of the footage will be slightly flickering due to the 50Hz AC supply in the lightbulbs vs the 60FPS camera shutter. Viewer caution recommended.

I can tie water into knots, don’t believe me?

Here’s a one-take magic show.

The part of the water jets before they just left the container looks uncannily still, and that is a little section of laminar flow. To be fair, it’s everywhere: your bloodstream, pipe workings, the air that makes possible a lenticular cloud, et cetera.

In more technical terms, a laminar flow is a flow with high momentum diffusion and low momentum convection. Here, the liquid moves in layers, with little to no mixing between layers.

In our demo, the flow is so steady that it almost keeps its shape, allowing us to manipulate the streams in ways not usually possible. If we bring two streams close together, by means of a wetting material, such as my hand, we can allow the surface tension to reshape the flows, which in turn is preserved over time.

More details to follow.

If you wish to play with this yourself, I recommend using a used beverage can or bottle. The holes can be drilled using a pin, and they should be spaced less than 0.5mm apart. Take care drilling holes, and please conserve water.

FW 2020. Today’s the 6th anniversary of my arrival to New Zealand .