# Aggregation and fragmentation dynamics in random flows: From tracers to inertial aggregates

## TL;DR

This study explores how aggregation and fragmentation processes in random flows influence steady-state size distributions of tracers and inertial aggregates, highlighting the effects of flow dynamics, particle properties, and binding strengths.

## Contribution

It introduces an individual-particle-based model to compare size distributions of tracers and inertial aggregates, revealing scaling behaviors and crossover phenomena.

## Key findings

- Size distributions vary with suspension dilution rate.
- Scaling relations can unify distributions with different binding strengths.
- Crossover occurs when aggregates exhibit mixed tracer and inertial behaviors.

## Abstract

We investigate aggregation and fragmentation dynamics of tracers and inertial aggregates in random flows leading to steady state size distributions. Our objective is to elucidate the impact of changes in aggregation rates, due to differences in advection dynamics, especially with respect to the influence of inertial effects. This aggregation process is, at the same time, balanced by fragmentation triggered by local hydrodynamic stress. Our study employs an individual-particle-based model, tracking position, velocity and size of each aggregate. We compare the steady-state size distribution formed by tracers and inertial aggregates, characterized by different sizes and densities. On the one hand, we show that the size distributions change their shape with changes of the dilution rate of the suspension. On the other hand, we obtain that the size distributions formed with different binding strengths between monomers can be rescaled to a single form with the use of a characteristic size for both dense inertial particles and tracer monomers. Nevertheless, this last scaling relation also fails if the size distribution contains aggregates that behave as tracer-like and as inertial-like, which results in a crossover between different scalings.