Laminar flow?


This popular video is shared with the following caption:

  • When water flows so smoothly it looks solid. This effect is called Laminar flow.

Update 1: I found the source. The “science”-spam accounts on Twitter and Facebook are sharing this video without description or link to the original. Video via Caters Clips:

Laminar flow occurs when a fluid flows in parallel layers, with no disruption between the layers. More details: Wikipedia.

Italian filmmaker Dario Bonzi posted this clip on Instagram. The description mentions “straight laminar flow”, but also contains hashtag #sciencejokes. Also, the YouTube video description mentions optical illusion. Are we really looking at laminar flow or some sort of a camera trick?

This trick can be done with a video camera taking pictures at 24 FPS and a speaker vibrating at 24 Hz (or 24 pulsations per second). The water appears as motionless. This is called the acoustic strobing effect. Further details: The Magic of Physics: A Water Spiral (Syfy). 

Watch the video below where Branden and Marisa demonstrates how the trick can be done. The water looks and behaves similar to that in Bonzi’s video. However, I cannot fully rule out other possibilities after finding the source.

Update 2: seems no trick was involved and the video might show laminar flow. I jumped into conclusions because the original source was unreliable. After finding the source, I started looking for possible similar cases and found one: https://www.iflscience.com/physics/this-water-stream-leaking-from-a-pool-looks-frozen-solid/. However, the source of that article is Reddit. Based on the comments on Reddit, many people are not convinced the video shows laminar flow.

I managed to contact Dario Bonzi via YouTube. Bonzi responded that video was made with iPhone at 2000 meters altitude in Italian alps without any tricks. If we rule out the camera trick, only one question remains: is this an example of laminar flow or something else?

Update 3, Laminar flow confirmed (December 21, 2018)

Andrew Steele contacted me on Twitter. They also contacted Dario Bonzi

Andrew Steele repeated the effect with a milk bottle (!):

Nobuhiko IZUMI also managed to repeat the effect:

These awesome experiments clearly show that the original laminar flow video by Dario Bonzi is real. This was a great example of false positive: initially I was sure of trickery because of the unreliable source. Also, Bonzi managed to film a rare video of laminar flow in which the water isn’t tube-like.

Categories: AccuracyTags:

2 comments

  1. This is not laminar flow, the water is looks bending several point which will make water turbulent and to be a laminar ow water must be free from turbulence. The water from pool is straight so that can be considered as laminar flow.
    There are several videos on YouTube White House can guide you to, how create apparatus to generate laminar flow.

    Like

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