DLA

What is it?

This program is a simulation of diffusion limited aggregation, where particles move randomly in the vicinity of a cluster until they collide with the structure and become part of it. The simulation starts with a single particle in the center of the screen, and then other particles are given random headings and positions positions (along a circle inscribed in the screen) and are moved forward until they collide with another particle. Particles are colored by their age, and the resulting formation is a dendritic fractal.

How to Use It

The SETUP button colors a few particles in the middle of the screen and prepares the program to run.

The GO button sends particles in motion.

The WIGGLE slider controls the maximum amount of a particle's random heading adjustment with each time step.

The STICKY? slider differentiates between two alternative detection methods for when a particle has collided with the group. When set to 0, a particle stops moving when any of the surrounding eight patches is occupied by a particle; when set to 1, a particles stops moving only when the patch directly in front of it is occupied.

Things to Notice

The fractal dimension decreases with higher values of wiggle, as random motion increases the probability of colliding with a particle on the outside of the structure. Similarly, the fractal dimension is lower with sticky? set to 0, as particles are more likely to be caught on the periphery of the cluster. With certain parameters, the model can create aggregations that closely reflect the 1.7 fractal dimension that is often found in nature.

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