Can there be applications of Graph Theory, Combinatorics etc. in PDEs mainly Hydrodynamics?

Tried my luck with Google's search engine, didn't show much info.
I guess you can try to use these features of GT and Combinatorics in QFT (there's a section in Kaku's book on QFT on Forrests and Skeletons from GT).

And what sort of applications are there?

I am asking, since I am thinking of taking courses in infinite combinatorics, axiomatic set theory and forcing this coming semester, and would like to know if it's not redundant. (As someone who likes to learn a lot it won't be redundant, but I guess I am asking would it have applications to PDE in Hydrodynamics).

I once in my search found a book on Categories in Continuum Mechanics by Lawvere, so perhaps there are such attempts to use algebra and combinatorics in Analysis.
https://link.springer.com/book/10.1007/BFb0076928