This was the first thing I did when I wrote a fluid sim as well - I’ve spent a ton of time and energy pursuing ways to get subtractive color effects (the richness and light-subjectivity of pigment) in digital artifacts and have mostly come up empty, but I take every chance I can get.
Have you checked out mixbox[0]? The outputs do feel intuitively "right" as someone who has dabbled in watercolor, and the paper/videos cover the thinking and Kubelka-Munk theory well.
