Near-wall interparticle collision dynamics in multi-phase turbulent channel flows

Interparticle collision statistics in a turbulent channel flow are obtained using direct numerical simulation coupled to Lagrangian particle tracking. The particle motion solver considers drag, lift, pressure gradient and added mass force contributions. Fluid momentum coupling and hard-sphere deterministic interparticle collisions are also accounted for. Collision behaviour for particle Stokes numbers outside of the range usually considered in similar investigations is discussed in detail. The analysis focuses on separating the turbulent channel flow into four regions of varying turbulence intensity. Collision velocities are analysed for each region and discussion as to how particles obtain those velocities is offered. The mean value of the collision angle is observed to scale with both Stokes number and wall proximity, with the former having the greatest effect. The greatest collision rate is found to be in the viscous sublayer and for the higher Stokes number.