What he's doing, writing CFD codes from scratch, is basically all math. You should be pretty comfortable solving PDEs by hand, then learn about the numerical solutions.

Unfortunately it takes a lot of persistence because mathematics is a huge precursor. Most people want bells and whistles but aren't willing to bunker down and learn partial differential equations and other context which can be less buzzworthy and somewhat mundane. I think math is cool though, its the language of complexity.

You can also start with simpler things, like drawing 3D graphs of equations, rendering and shading 3D shapes, and plotting Mandelbrot sets. For me, that was fun and visual, with simpler math. Example of sin(x)+cos(y) : http://maxima-online.org/examples.html

Do you want to learn how to use graphics APIs to do cool stuff? Or create graphics API's, using cool math? Or learn CPU/GPU innards?