This is incredibly fun to play with.

But the project doesn't explain who is intended for. Could I get some background info?

Project author here. The gallery is part of scientific software Aphros https://github.com/cselab/aphros for flow simulations. Examples in the gallery demonstrate what physical problems can be solved. The same configuration can be used on larger computers (including supercomputers). Intended for potential users of the software and those willing to learn some fluid mechanics.

Here's a post by the other author of the project https://news.ycombinator.com/item?id=26492582

Would love to see a tesla valve

I started making one https://tinyurl.com/yj8g3rzp but doing it with primitives (circles and boxes) is too painful.

We will probably add a geometry editor later.