Chaotic Waterwheel by Harvard Natural Sciences Demonstration

Edward Norton Lorenz (1917–2008) was not a mathematician, computer scientist, physicist, or meteorologist, but he was all of these at the same time: a great scientist who left a lot of work for all these occupations. Even he invented a Chaotic Waterwheel to clarify his idea and explanation about chaos.

The Chaotic Waterwheel is recognized and known for its random or unpredictable chaotic movement.

Today, we shall watch a captivating and famous physics demonstration named Chaotic Waterwheel. This demonstration video was created and filmed by Harvard Natural Sciences Lecture Demonstrations and presented on their Youtube channel and published on May 13, 2020

We propose here to revisit and study a classic mechanical device to clarify the interpretations predicted by the Lorentz equations, called…

Chaotic Waterwheel By Harvard Natural Sciences Lecture Demonstrations

How Does It work? The Waterwheel Work-Principle

  1. An inclined wheel carries leaky (with draining holes) buckets.
  2. There is a tap connected to a pump which is fixed directly above the centre of the wheel.
  3. The tap pours water, filling the cups as they pass under the stream.
  4. The leaky buckets are drilled and empty slowly.
  5. The wheel starts to move according to the weight of the buckets.

This Chaotic Waterwheel is special because its movement is unpredictable. random, or chaotic. Even small variations change its speed and direction of rotation. Moreover, no current computers can predict their movement for more than two minutes.

The classic version of this mechanism can be seen at the Cité des sciences et de l’Industrie in the Parc de la Villette in Paris.

The Making Of The Waterwheel Model

The idea of designing a Water wheel was a mechanical example of a chaotic system that was introduced and realized by Louis Howard, Willem Malkus, and Ruby Krishnamurti at the beginning of the 70s.

The waterwheel with leaky (with draining holes) buckets sustains chaotic movement. The wheel has about one-meter diameter. It was fabricated with wood. The little leaky buckets are citronella candle holders with ¼ inches holes drilled out of the bottom for draining the water from inside. To evacuate water from the bottom to reuse, there was a sump pump installed (mostly available at local hardware stores). A ball valve at the faucet was set to regulate the water flow. Then the wheel and the sump pump, both installed in a concrete mixing tub. (If you will make this design by yourself at home, the demo will splash water all over your place, so make sure to keep a mop handy 😋!)

The tub was filled with a few inches of water. And the faucet was aimed at the centre of the axle. Then the start happened with the closed ball valve and gradually opened to provide enough flow rate to have enough energy to overcome the friction. And the makers gave a chance to the buckets to drain out the bottom without overflowing. Finally, some coins and modelling clay have been used to set the scale of the wheel. And the waterwheel is ready for demonstration.

The key purpose of the demo is to display chaotic, or at least random motion, which means the makers did not want to have the waterwheel proof a continued rotation in just one direction.

However, in nature, the chaotic behavior quickly happens in turbulent flows also in large-scale climate patterns, though comparing those systems to a lab or classroom framework is far from insignificant.

According to Edward Lorenz, “The design was a precision device, suitable for controlled lab experiments.” But the remake of the original design is simple and equipped more towards pedagogical force than experimental accuracy. However, by watching and understanding this video and making, you will get the charm and enlightening learning of the original Waterwheel concept.

Why Are the Natural Sciences Lecture Demonstrations Important?

The Scientific demonstration has a long tradition in science education. It has long been considered a significant tool for literally “demonstrating” certain natural phenomena or illustrating the scientific concepts used to describe these same phenomena. In such a context, the demonstration is often considered as a privileged educational tool to enrich teaching taking the form of a masterful presentation. A Demo is essential to point out the other missing things in science and serves to present and draw attention to a natural phenomenon. Why?

  1. To start an investigation (why is this happening?).
  2. To provide a visual aid that strikes the imagination and facilitate the acquisition of concepts.
  3. To give an example of the application of a principle.

Edward Norton Lorenz (1917–2008)

This text is a tribute to Edward Lorenz (1917-2008), who was a Meteorologist but also a Physicist and a Mathematician. In the years 1960-70, he highlights The butterfly effect which has become famous, even outside the scientific world. He was not the first to introduce the concept of dependence sensitive to initial conditions, or chaos; Jacques Hadamard and Henri Poincare had understood most of it at the end of the 19th century, in the context of celestial mechanics.

But these ideas remained theoretical and the people did not imagine that they could have repercussions in everyday life, such as the weather tomorrow. Absolutely, Edward Lorenz benefited from the help of genius predecessors. As Lorenz had the good fortune to work at a time when computers were finally becoming efficient; but all this does not detract from the fact that he understood in depth a phenomenon that seemed a curiosity to theorists. And that he was able to explain that we can see this phenomenon almost everywhere. We had attempted to explain here that his contribution to chaos theory goes well beyond.


This post of The chaotic waterwheel isto pay homage to the extraordinary physical sense of Edward Norton Lorenz. He had the idea to design a much simpler physical system, a waterwheel, which obeys these simplified equations.

A physicist always likes “real experiments.” So, his design will help us understand Lorenz’s main ideas. Here, Harvard Natural Sciences Lecture Demonstrations made a quick and remarkably simplified Chaotic Waterwheel as a reminder of the history of the physics of movement and time, which we call dynamics.

Thank you for your visit, keep experimenting with Harvard Natural Sciences Lecture Demonstrations!


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