Influence of Particle Aspect Ratio on Translational Collision Dynamics in Wall-Bounded Turbulence

This study examines how particle shape influences collision dynamics in turbulent channel flow using direct numerical simulation (DNS) with Lagrangian tracking and fully resolved four-way coupling. Rigid ellipsoids across aspect ratios are simulated with inertia-driven translation, hydrodynamic forces, and quaternion-based rotation. Needle-like particles align more strongly with the local shear, reducing turbulent scattering and producing lower collision velocities with narrower angle distributions. Nearly spherical particles respond more intensely to turbulence, yielding broader collision statistics. Some features, such as spanwise velocity fluctuations, remain largely shape-independent, highlighting the dominance of lateral turbulent motions.