Effect of Reynolds number and system size on turbulence modification in particle-laden channel flow*

Turbulent particle-laden flows find many applications, starting from pneumatic transport of solid to separation of particulate from industrial exhaust. The presence of particles in particle-laden turbulent flows can augment or attenuate the turbulence level of the gas phase. Earlier studies have shown that modification of turbulence intensity varies with mass loading, Stokes number, Reynolds number and ratio of channel width to particle diameter (L/dp) [Tanaka and Eaton, PRL, 2008]. The phenomenon of turbulent modulation is complex and cannot be defined with a single parameter. Coupled LES-DEM simulations have been carried out for different volume fractions and Reynolds numbers with different L/dp ratios to investigate the turbulence modulation in the gas phase. In the present work, we have quantified the effect of L/dp and channel Reynolds number on discontinuous attenuation of turbulence intensity as a function of particle volume loading in a vertical channel flow. It is observed that the extent of attenuation decreases with decrease in L/dp ratio. Also, an increase in Reynolds number subside the phenomena of particle-induced attenuation.