Effect of Reynolds Number on Critical Stokes Number Particle Collision Statistics in Multiphase Turbulent Channel Flows

Spherical particle collision statistics in multiphase turbulent channel flows are obtained using a Lagrangian particle tracking algorithm four-way coupled to direct numerical simulations. Two channel flows are simulated at Reτ=180 and Reτ=590 with particles of the Kolmogorov Stokes number StK=1. Particle collision velocities and angles within four regions of the channel flows (viscous sublayer, buffer layer, log-law region and bulk flow) are analysed to elucidate the dynamics of particle interactions in the various regions of the turbulent flows. The results indicate that the most significant contribution to collision velocities arises in the streamwise direction, with particles in the viscous sublayer region colliding with lower streamwise velocities compared to those in other regions of the flow. Furthermore, the spread in the distribution of collision angles is found to be highest in the viscous sublayer, and lowest in the bulk flow region.