Fully resolved binary particle interactions in isotropic turbulence using hard and soft sphere collision models

Binary particle collisions have been studied using hard and soft sphere collision models in both stagnant fluid and boxes of homogeneous isotropic turbulence. Particle-fluid coupling was achieved using a ghost-cell immersed boundary method coupled with the spectral element method-based direct numerical simulation solver, Nek5000. The turbulent box was obtained using the stochastic forcing technique with a Reynolds number based on the Taylor microscale Reλ ≈ 2.5, chosen to represent the viscous sublayer in a Reτ = 180 channel flow. Results in stagnant boxes indicate that discrepancies between the two models increase at velocities close to the agglomeration-rebound transition region, though fair agreement between the two models is observed for Monte Carlo-based simulations in homogeneous isotropic turbulence, with the soft sphere model more likely to predict agglomeration given a single collision event.