That's right. Oliver Hunt wrote a full simulator and released it under MIT, which was so perfect as I was just starting to look into fluid dynamics myself, for what ended up being this website. I used his physics calculator component almost verbatim, and wrote the display/ui stuff I needed around it as though I were using a library.

I've done more serious touching of it, for performance reasons -- taking mults and invariants out of loops, or memoizing for example -- but I always ended up either breaking it or making it slower, so for now I've settled with leaving it alone!