Why do some teapots dribble?
Pouring flows
Two mathematicians calculated why teapots dribble down their spouts, and how to design one that doesn’t.
Ig Nobel 1999
Jean-Marc Vanden-Broeck and Joseph Keller wrote the equations for liquid pouring over the lip of a container, the kind of flow you get from a teapot spout.
At slow pours the liquid likes to curl back and hug the outside of the spout. A sharper lip helps the tea let go cleanly, which is why some teapots drip on the tablecloth and others behave.
The teapot that dribbles isn’t clumsy. It’s just obeying the maths.