Particle-resolved direct numerical simulation of particle-laden turbulent channel flow

Particle-resolved direct numerical simulations for particle-laden turbulent channel flow are performed by lattice Boltzmann method coupled with discrete element method. The modulation effects of particles on turbulent flow and spatial particle dispersion are studied under wide particle-to-fluid density ratio (ρp/ρf) ranging from 1.5 to 10 and solid volume fraction (ϕv) ranging from 2% to 20%. Simulation results indicate that as ρp/ρf increases, the overall turbulent kinetic energy (TKE) decreases, and the peak of TKE shifts from wall to channel center. Correspondingly, the peak of particle cluster grows higher, and particle distribution becomes more uniform further away from cluster, which can be revealed through both Shannon entropy and local solid phase volume fraction. Additionally, at low ρp/ρf, a dense distribution with a concentration higher than average ϕv forms at a channel center. With increasing ϕv, TKE is enhanced near wall and diminishes at the channel center, due to the fact that the particle cluster obstructs the influx of wall vortices into the channel center. With further increases in ϕv, mainstream velocity first weakens to zero, then reverses and intensifies. Particle cluster at the channel center can occur under both high and low ϕv, which essentially related to mainstream velocity.