Turbulent breakage of ductile aggregates

TL;DR

This study investigates how ductile rupture affects the breakage rates of colloidal aggregates in anisotropic turbulence, revealing that ductile rupture significantly reduces breakage rates compared to brittle rupture due to energy absorption dynamics.

Contribution

It introduces a detailed analysis of ductile rupture in turbulent flows, highlighting the differences from brittle rupture and providing new insights into aggregate breakage mechanisms.

Findings

Ductile rupture reduces breakage rates compared to brittle rupture.

Energy absorption during ductile rupture influences breakage statistics.

Anisotropic turbulence affects the energy distribution and rupture outcomes.

Abstract

In this paper we study breakage rate statistics of small colloidal aggregates in non-homogeneous anisotropic turbulence. We use pseudo-spectral direct numerical simulation of turbulent channel flow and Lagrangian tracking to follow the motion of the aggregates, modelled as sub-Kolmogorov massless particles. We focus specifically on the effects produced by ductile rupture: This rupture is initially activated when fluctuating hydrodynamic stresses exceed a critical value, $\sigma>\sigma_{cr}$, and is brought to completion when the energy absorbed by the aggregate meets the critical breakage value. We show that ductile rupture breakage rates are significantly reduced with respect to the case of instantaneous brittle rupture (i.e. breakage occurs as soon as $\sigma>\sigma_{cr}$). These discrepancies are due to the different energy values at play as well as to the statistical features of energy distribution in the anisotropic turbulence case examined.