This is definitely a good site that covers what complexity science is about. Good resource that I found a fascinating read.
The flow of water through a pipe is still in many ways an unsolved problem.
— Read on arstechnica.com/science/2018/10/turbulence-the-oldest-unsolved-problem-in-physics/
This is a great overview of turbulence. An issue that has practical impact in the bio pharmaceutical space and has created a few interesting deviation trends in my experience.