(146h) RANS Modeling of Cluster-Induced Turbulence in Particle-Laden Channel Flow

A phenomenon often observed in gas-solid flows is the formation of mesoscale clusters of particles due to the relative motion between the solid and fluid phases that is sustained through the dampening of collisional particle motion from interphase momentum coupling inside these clusters. The formation of such sustained clusters, leading to cluster-induced turbulence (CIT), can have a significant impact in industrial processes, particularly in regards to mixing, reaction progress, and heat transfer. One of the challenges in successfully resolving these clusters through Eulerian-Lagrangian simulations in previous work has been the requirement for an overwhelming degree of refinement of the modeled geometry. A less computationally expensive model is needed to model and study CIT in practical applications. This work implements a two-phase Reynolds-Averaged Navier-Stokes (RANS) model to capture the wall-normal flow characteristics in fully developed channel flow with CIT. Dilute and moderately dense concentrations of particles are considered and compared with both high-resolution Eulerian-Lagrangian and Euler–Euler anisotropic Gaussian simulation results. The mean gas velocity is varied to study the relative importance of shear vs. cluster-induced turbulence for fixed mass loading of particles. The inclination of the channel geometry is also varied to examine the effect of the direction of gravity relative to the direction of flow on cluster formation and turbulence statistics.