Introduction
We have all seen liquid running out of containers through holes in the bottom.
The physical principles involved are the same whether the vessel is
a bucket with a hole in it or an industrial tank being drained during
a manufacturing process. Frequently it may be advantageous to drain a
container as rapidly as possible. An obvious way to do that, of course, is
to make the drain as big as possible. But other constraints usually make
that impractical.
So, what is it that governs the drainage rate driven by gravity? This is not
a trivial question, but instead raises a potentially significant engineering
issue concerning the proper shapes of industrial vessels.
Stated more formally, given a smooth, well-rounded orifice for a drain,
what is it that governs the rate at which a container will drain?
Perhaps even more important is what determines the total time
required for a given container to drain completely. Do all containers
holding the same volume and identical drains empty at the same rate? Are
the rates constant? If not, what is it that affects the rate? These are
not trifling questions. In the world of commerce, time is money.
In this project, we will consider three different containers, all with
exactly the same total volume and with identical drain orifices. What's more
each container will have the same initial level of fluid, measured
from the drain orifice in the bottom. The shapes we will consider are:
1) a circular cylinder, 2) a section of a cone with the
small end down, and 3) an identical section of cone with the
large end down. Other shapes can also be investigated, but the principles
are illustrated with these simple cases.
Boyd Gatlin
Associate Professor of Aerospace Engineering
Mississippi State University