Chute flow as a means of segregation characterization
2014
Bhattacharya, Tathagata | McCarthy, J.J.
Handling of granular materials involves the use of many solids processing devices such as chutes, hoppers, tumblers or other transfer equipment. Unfortunately, granular materials segregate if they are subjected to flow or external agitation in the presence of a gravitational field. Thus, operation of many of these devices is prone to segregation. Many studies of granular flow have focused on gravity driven chute flows owing to their practical importance in granular processing and to the fact that the relative simplicity of this type of flow allows for development and testing of new theories/equipment. In the present work, we observe the deposition behavior of both mono-sized and polydisperse dry granular materials in an inclined chute flow, both experimentally and computationally. We investigate the effects on the mass fraction distribution of granular materials of different parameters such as chute angle, particle size, falling height and charge amount. The simulation results obtained using the Discrete Element Method (DEM) are compared with the experimental findings and a high degree of agreement is observed. Tuning of the underlying contact force parameters allows realistic results and is used as a means of validating the simulation model against available experimental data. The tuned simulation is then used to test predictions of granular segregation theories outlined in previous studies. That is, it has been predicted that a system can maintain a mixed configuration when L<Uavgts, where L, Uavg, and ts denote the length of the chute, the average stream-wise flow velocity of the particles, and the characteristic time of segregation, respectively. Our results with the tuned simulation support these conclusions for chute flows.
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