Edit: He also says it's full engineering accuracy, not cheap CGI CFD that only has to look plausible. You could extract pressures, forces from the surfaces and use it for analysis. He's done extensive validation for his academic work.
The way they decided to use the wind to guide players to the next point of interest is also an interesting concept in the minimap-plagued open world genre.
-[0]: https://www.gdcvault.com/play/1027124/Blowing-from-the-West-...
[1]: https://docs.blender.org/manual/en/2.79/physics/fluid/types/...
Real fluids are just approximations of the ideal. :) Their fundamental flaw is not being truly continuous, but rather consisting of sticky molecules. Surface tension is caused by the imbalance of forces acting on molecules not surrounded by other molecules on all sides: