“What is a flow field? Think of your Processing window as a grid. In each cell of the grid lives an arrow pointing in some direction—you know, a vector. As a vehicle moves around the screen, it asks, ‘Hey, what arrow is beneath me? That’s my desired velocity!’”
Chapter 6.6 Flow Fields: http://natureofcode.com/book/chapter-6-autonomous-agents/
We are using Flow Fields to elucidate the environment with the movements of the microbes.
I am using a paper called "Computational Fluid Dynamics of Sponge Aquiferous Systems" as a scientific reference and pulling some artistic license as to how microbes may move in an urban environment.