Also known as a vector field, this technique involves assigning a unique vector to each point in a 2D or 3D space describing the direction and magnitude of varying forces. Flow fields are often used together with particle systems to model complex, dynamic movement caused by wind, fluid flow, electromagnetism, and more.

Vector fields are often populated using data generated with noise or image data. Curiously, flow fields have also been used in pathfinding.

Articles:

• Vector field on Wikipedia
• Flow Fields, Part I by Keith Peters
• Flow Fields, Part II by Keith Peters

Code projects:

• ofxVectorField (openFrameworks add-on) by Jeremy Rotzstain (mantissa)

Videos:

• Coding Challenge #24: Perlin Noise Flow Field by Daniel Shiffman (Github repo with source code for p5.js and Processing)