Modeling the formation mechanism and growth rate of aggregates through Brownian dynamics

Microorganisms and particulates present near the ocean surface tend to form clusters when coming into contact with each other. The resulting marine aggregates exhibit a fractal structure and play a fundamental role in the oceanic carbon cycle. Our research aims to numerically model their formation using Brownian dynamics. In our model, aggregates undergo random translation and rotation, and they can also be allowed to settle under gravity. They attach to each other when within a predefined distance threshold. We quantify the fractal dimension and growth rate of the aggregates for constant and size-dependent diffusivities and for various settling speeds.