Simulation of diffusion-limited aggregation: effects of launching boundary shape and non-fixed centre

Abstract Simulations of the Witten—Sander model of diffusion-limited aggregation (DLA) were performed using modified versions in which a square launching boundary and a non-fixed centre were adopted. Square launching boundary leads to an isotropic fractal instead of the diamond-shape cluster found in the conventional simulation using circular releasing boundary. The nonfixed centre model displays a similar feature as that found in Levy-flight-trajectory simulations which bridge two limiting aggregation models, i.e. the Eden model and the Witten—Sander model.