Dynamics and Collision of Non-Spherical Ellipsoid Particles in Turbulent Channel Flow

Non-spherical particle-laden flows in pipes and channels are of importance in numerous industrial, environmental, and biological processes, making their study essential for understanding and optimising particle transport, deposition, and interaction dynamics. In this work the spatial and orientational dynamics of rigid ellipsoidal particles in turbulent channel flow are explored. A high-fidelity spectral element method-based direct numerical simulation is employed to solve for the fluid phase which is coupled to a Lagrangian particle tracker for modelling the dispersed particles. Particle translational motion is governed by inertia, hydrodynamic lift, and drag, while their rotational dynamics is described by the Euler equations of rotation, accounting for external hydrodynamic torques. Quaternions are utilised to track particle orientations over time. Full four-way coupling between the particles and the fluid is implemented, capturing both the influence of the fluid on the particles and the feedback effect of the particles on the continuous phase. The latter is modelled using a local element-based force feedback field in the Navier-Stokes equations. Particle-particle collisions are also resolved. The fluid and particle phases are validated across multiple particle aspect ratios, Reynolds and Stokes numbers with emphasis on reproducing spatial and orientational dynamics consistent with the literature. Fully coupled simulations are then conducted to evaluate collision statistics across all regions of the channel with results being compared to those of spherical particles to elucidate the underpinning micro-scale dynamics present in such flows as well as providing avenues for further research.