Diffusion Limited Aggregation

I first came across Diffusion Limited Aggregation while taking Josh Deutsch's class on mathematical modelling in the UCSC physics department. It was one of the first scientific computing applications I'd encountered. My previous programming experience was mostly in games, websites, programming microcontrollers for electronics projects, and general hacking about.

I coded a basic C implementation that simulated DLA aggregating against a seed at the center of the field, with periodic boundary conditions. I remember it taking a few minutes on my MacBook to reach the boundary of a 1000x1000 grid—clearly not very efficient! Amazingly, I think I used a PostScript driver to output the result to avoid writing graphics code. Not sure how that counted as "simple."

I was thinking about that project this afternoon, so I built a small app that recreates the idea. It lets you invert the simulation by placing a source in the center and drawing a boundary around the outside. You can see the app below, or check out the source code here: github.com/Neutron-Tom/dla.

Interactive Simulation

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