Turbulence modification of particle-laden flow in horizontal rectangular duct

Pneumatic conveying is used to transport solids in many chemical and pharmaceutical industries. Despite its high industrial relevance, the different types of interactions, like the particle–turbulence, particle-particle, and particle–wall for wall-bounded flows, are not well understood. The objective of the present work is to understand the two-phase dynamics of the particle-laden flow in a horizontal rectangular duct. Simulations are performed using the Eulerian-Lagrangian framework considering turbulent fluid medium as the continuum, and the particles are discrete Lagrangian point particles. Although point particle approximation is used to calculate drag force on the particles, their finite size effect is considered to simulate particle-particle and particle-wall interactions. The duct used in the present investigation has a cross-section of 4:1. Two-way coupling is used with the De-Felice equation to model the drag. Dynamic one equation LES is coupled with DEM for the particle phase. Simulations are performed using both perfectly smooth and rough particles, where linear spring-daspot model is used considering normal coefficient of restitution of 0.9. The mean velocity profiles for the gas and particle phases and the second moments of the velocity fluctuations are computed. It is observed that the fluid Reynolds stress decreases with the increase in the mass loading ratio, and a turbulence collapse is observed for the mass loading ratio of 1.0 when the particle Stokes number is 82.