What Determines Size Distributions of Heavy Drops in a Synthetic Turbulent Flow?

TL;DR

This study uses a particle-based model to analyze how collision, coagulation, and fragmentation processes in turbulent flows determine the size distribution of heavy drops, highlighting the effects of different fragmentation mechanisms.

Contribution

It introduces a particle-based modeling framework that captures particle inertia effects and compares two fragmentation mechanisms in turbulent flow conditions.

Findings

Size-limiting fragmentation mainly affects the maximum stable particle size.

Steady state depends on particle and flow properties in shear fragmentation.

Scaling relationships are derived linking steady state to flow and particle parameters.

Abstract

We present results from an individual particle based model for the collision, coagulation and fragmentation of heavy drops moving in a turbulent flow. Such a model framework can help to bridge the gap between the full hydrodynamic simulation of two phase flows, which can usually only study few particles and mean field based approaches for coagulation and fragmentation relying heavily on parameterization and are for example unable to fully capture particle inertia. We study the steady state that results from a balance between coagulation and fragmentation and the impact of particle properties and flow properties on this steady state. We compare two different fragmentation mechanisms, size-limiting fragmentation where particles fragment when exceeding a maximum size and shear fragmentation, where particles break up when local shear forces in the flow exceed the binding force of the particle. For size-limiting fragmentation the steady state is mainly influenced by the maximum stable particle size, while particle and flow properties only influence the approach to the steady state. For shear fragmentation both the approach to the steady state and the steady state itself depend on the particle and flow parameters. There we find scaling relationships between the steady state and the particle and flow parameters that are determined by the stability condition for fragmentation.