Imprints of turbulence on heterogeneous deposition of adhesive particles

TL;DR

This study uses direct numerical simulations to investigate how turbulence and temperature-dependent adhesion influence the heterogeneous deposition patterns of particles on walls, revealing significant implications for wall wear.

Contribution

It introduces a combined turbulence and temperature-dependent adhesion model to analyze particle deposition heterogeneity and its impact on wall wear.

Findings

Deposition is highly heterogeneous, especially for inertial particles.

Deposited particles form streaks with characteristic spacing related to velocity correlations.

Localized wall wear can be over ten times the average due to clustered particle deposition.

Abstract

We present direct numerical simulations (DNS) of particle deposition in a turbulent channel flow, incorporating a viscoelastic soft-sphere collision model with temperature-dependent van der Waals adhesion. Particle-wall contact is governed by an adhesion number that varies with temperature, enabling exploration of a wide range of deposition behaviors. Deposition is strongly heterogeneous, especially for inertial particles, where rolling and sliding enhance nonuniformity. Spanwise radial distribution functions reveal that deposited particles form streaks with characteristic spacing set by near-wall two-point velocity correlations. A clustering metric confirms that high-inertia, low-adhesion particles deposit in elongated, anisotropic patterns due to spanwise migration driven by velocity fluctuations. Finally, it is shown that this heterogeneity in deposition leads to localized wall wear rates exceeding ten times the mean, with the most severe wear associated with particles that are carried to the wall in clusters by sweep events.