Links on fluid dynamics:
http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html (great site for general physics and particularly on fluids, http://hyperphysics.phy-astr.gsu.edu/hbase/fluid.html#flucon )
http://www.uvi.edu/Physics/SCI3xxWeb/Plumbing/Plumbing.html (Fluid statics and fluid dynamics section. Great reading if you need to understand how the plumbing in your house works...).
Random-Walk Simulations
There are a number of good simulations on the web. They appear and disappear, so try searching under "1D Random Walk Simulations" or "2D Random Walk Simulations."
Currently (17 February 2003), here are some that you might like:
One of my favorites is a 2D simulator that hangs on to past simulations, so you get the mean picture as well as individual runs. It also links to a 1D simulator. This pair of simulators is so fast, however, that they can be confusing.
There are some java applets that do some of these simulations, but they display in some strange ways on some machines.
A Dutch applet gives you the opportunity to change probabilities.
These simulations are a lot like your homework.
Other useful references:
A source for great problems and solution strategies in environmental sciences is: Harte, J., 1988, Consider a spherical cow, University Sciences Books, 283pp.