This is an ok introduction to CFD in that you discretize a problem, but it is not insightful and not scientific in its approach. The author routinely admits he doens't know how certain portions of the code work.

This is a much better approach to CFD / Navier-Stokes and will help you understand the various phenomenon along the way. https://lorenabarba.com/blog/cfd-python-12-steps-to-navier-s...

Agreed. I started from this article a few years ago, and was frustrated enough by:

> So that means, while I know what it does, I don't really know how, since all the work is in that mysterious function.

that I spent the time to work it out myself. (answer: It arises from discretising the Laplacian -- 6 is the number of direct neighbours in 3D)

CFD start to become really painful when the fluid leaves the cells...