We added large surface area flags to enhance the response of the flow sensing units in caves were the water was flowing slower than 1 cm/s. But like most of my rough & ready DIY solutions, turning the boosted sensors output into something quantitative is a challenge.

In the process of figuring that out I bumped into an equation solver called Eureqa which offers a way to characterize empirical relationships like this in mathematical terms. It's also kind of fun to use (even for a non-mathematical person like me) as you can tweak it in so many ways. Although my application was fairly trivial, I suspect that the program could be very useful to other projects listed here.