I am writing to present a novel device that demonstrates the counterintuitive trajectory of water as it flows down on what appears to be a uniformly smooth surface (Fig. 1). While our intuition anticipates a linear descent by gravity, this simple device reveals a mesmerizing display of meandering water flow. Minute surface imperfections, such as microscopic scratches or variations in wetting ability resulting from surface coatings, introduce an element of randomness to the water stream, as shown in the accompanying image. (Red food coloring was added to the water for visual effect.) An online video of the demonstration is available.1 
Fig. 1.
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Meandering water flow.

Fig. 1.
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Meandering water flow.

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Made of acrylic sheet stock, the device is a sealed thin enclosure featuring two internal partitions, each equipped with two small gaps. Instructions for fabricating similar enclosures are...

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