system
Given the following post, respond as if you're commenting on Reddit:
human
I would have thought that by now the optimum spout-shape (as on jug or kettle) is longsince known - that is, 'optimum' in terms of water falling cleanly from the spout & not dribbling back along the underside of it: so does anyone know whether such an optimum spout exists?

And if so, then why it's not so that _absolutely all_ spouts are made that shape. 

I don't think such a spout-shape could be _calculated_ ... so I'm not asking for a _mathematical equation_ for the curve of it (unless it be a _parametrised empirical_ one). Also such a shape, if it does exist, has possibly been known for two or three millenia ... or _yet longer_, maybe!

Actually - it's just occured to me now that _each individual material_ might have its optimum shape, according as the affinity of water for substance varies from one substance to the next.

This question was infact prompted by an actual act of pouring water from a jug, & thinking "that spout could be a better shape than that!".
gpt
I suspect that an 'optimum pouring' spout might be impractical, since 'not dribbling back' can probably best be achieved with a sharp edge (fluids flowing along a smooth surface tend to adhere to it, whereas a sharp corner can break the adhesion). Depending on the material the container is made of, this would liable to be easily damaged and/or hazardous.