(432b) Modeling Segregation in Modulated Granular Heap Flow | AIChE

(432b) Modeling Segregation in Modulated Granular Heap Flow


Deng, Z. - Presenter, Northwestern University
Xiao, H., Northwestern University
Lueptow, R., Northwestern University
Ottino, J. M., Northwestern University
Umbanhowar, P. B., Northwestern University
While granular segregation in steady flows has been investigated and successfully modeled for various operating conditions and geometries in previous studies, segregation in unsteady granular flows, though present in many industrial applications, remains largely unexplored. In this study, we focus on stratification in unsteady size-bidisperse bounded heap flow. Experiments show that periodically changing the feed rate of particles falling onto the heap results in stratified segregation similar to that which occurs at low feed rates, but with more regular stratified layers of large and small particles and a higher overall feed rate. We model this stratification in a bounded heap using the unsteady form of the advection-diffusion-segregation equation. Simply repeatedly switching the model from a low volume flow rate to a high volume flow rate instantaneously along the entire length of the flowing layer results in stratification patterns similar to those observed in experiments. Higher fidelity is achieved with a flow kinematics model that describes the downstream-moving front of particles after a change in the flow rate. Quantitative agreement of continuum model predictions with experiment over a range of operating conditions validates our modeling approach. The research is funded by NSF Grant #CBET-1511450.