Method of Solution
Method of Solution
The two equations we arrived at above are both ordinary
differential equations. In principle, we should have enough tools
at our disposal to solve them by hand, given enough time to eliminate
all the errors. Before we decide how to attack them
mathematically, however, let's rearrange them a bit.
For the circular cylinder, we can easily separate the variables, putting all
functions of y on one side and all the constants and t on the
other side:
Rearranging the equation for the conical tank requires a bit more
algebra:
As noted above, r is the minor radius of the cone section,
is the major
radius, and
is the radius of the drain.
Both of these equations appear to be soluble analytically, although (13) may
be quite tedious. In either case, it may not be possible to find an explicit
expression for y(t). That is, the solution may be
in the form of a transcendental or some other function which does not allow
us to isolate the solution on the left and the independent variables and
constants on the right. In that case, it may make sense to evaluate
t(y), if that is more easily plotted.
Boyd Gatlin
Associate Professor of Aerospace Engineering
Mississippi State University