The Pythagorean Cup

How a cup drinks itself — cut open, measured, explained.

Parts — hover or click

Pick a part to see what it does.
Said to be invented by Pythagoras of Samos (~530 BC) to ration wine: take your fair share, or leave with nothing. The model is real 1-D hydraulics in centimetres; three things are simplified: the slug that primes the tube is taken to fill the bore from the crest at the overflow rate, losses are lumped into one discharge coefficient spread along the path, and the waves, droplets and bubbles are decoration.