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(321g) RANS Modeling of Cluster-Induced and Shear Turbulence in Particle-Laden Channel Flow

Authors: 
Baker, M., Iowa State University
Fox, R. O., Iowa State University
Desjardins, O., Cornell University
Capecelatro, J., Cornell University
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. Both dilute and moderately dense

concentrations of particles are considered and compared with high-resolution Eulerian-Lagrangian

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.