Click the green flag. The particles move about randomly (colored red) until they touch a stationary particle (colored green).
Patterns that look like ferns or coral appear. These are similar to what you see when you drop dye into glue, which is called viscous fingering. A similar pattern is seen in crystal formation, coral, fungi growth, liquid seeping through soil, and even lightning. In this model, called diffusion-limited aggregation, particles moving (diffusing) randomly stick together (aggregate) to form treelike branching fractal structures. Diffusion-limited aggregation happens to model other processes, such as viscous fingering, in which a less viscous liquid presses through a more viscous liquid. The finger-like projections result from pressure being somewhat greater at the tips. We imitated a diffusion-limited aggregation model in NetLogo: https://lifepatternsemerging.com/wp-content/uploads/2020/11/DLA-additive-stickiness.html
