Numerical modelling of inertial fibre-like particle transport in micron-scale rough horizontal channel flow

Particle-laden turbulent flows involving non-spherical particles are encountered in a wide range of industrial and environmental applications, where particle–wall interactions and surface roughness play a crucial role in determining particle transport and deposition. In this contribution, a turbulent horizontal channel flow laden with inertial particles is investigated using LES/CFD-DEM method, considering both spherical particles and elongated fibres with varying aspect ratios. The influence of wall roughness is examined by comparing smooth- and rough-wall configurations, where the roughness affects exclusively the dispersed phase. The results demonstrate that wall roughness has a pronounced impact on particle dynamics, significantly modifying particle concentration distributions, velocity profiles, and near-wall behaviour. Rough walls enhance particle resuspension and alter particle trajectories, leading to stronger concentration gradients and reduced near-wall accumulation compared with the smooth-wall case. A direct comparison between the simulated transport of spherical particles and experimental data shows good agreement for mean flow and particle velocities. Beyond spherical particles, the particle elongation effect is also compared. Increasing the fibre aspect ratio is found to alter particle-flow coupling and near-wall dynamics, leading to distinct clustering and rotational behaviours. Less elongated fibres present enhanced preferential concentration and increased rotational velocities near the wall, driven by reduced rotational inertia and less constrained particle–wall collisions. On the other hand, fibres with higher aspect ratios experience reduced rotational motion and noticeable different near-wall dynamics.