Mike Hord wrote:

> I'd like to make some fountains for my home, and I'm wondering if anyone
> has any input. 
> 
> In particular, I'm wondering about an equation describing the behavior
> of a stream of water emerging from a hole in a reservoir.  Google search
> terms are proving elusive.  It seems to me that the equation should be
> pretty simple, based on depth of water and size of hole.  The result
> should be a half-parabola.

It seems to me that you have a pressure (the depth of water above the hole)
and a resistance (basically a function of the diameter of the hole, I
assume). That would determine the speed at the hole. The rest is
(simplified) vector arithmetic with gravity: The speed component at the
hole will remain constant (approximately), and the speed component caused
by gravity will increase according to the known formula.

Not sure where you'd find the resistance of a hole (or a short pipe). I
have a handbook here with some diagrams (for longer pipes, which could
possibly be extrapolated), but that won't help you much :)  But probably
someone else can give you a tip -- or this helps you already to google for
something.

Gerhard

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