Granular segregation in a thin drum rotating with periodic modulation

Abstract

We present the results of an experimental investigation into the effects of a sinusoidal modulation of the rotation rate on the segregation patterns formed in thin drum of granular material. The modulation transforms the base pattern formed under steady conditions by splitting or merging the initial streaks. Specifically, the relation between the frequency of modulation and the rotation rate determines the number of streaks which develop from the base state. The results are in accord with those of Fiedor and Ottino [J. Fluid. Mech. 533, 223 (2005)], and we show that their ideas apply over a wide range of parameter space. Furthermore, we provide evidence that the observed relationship is maintained for filling fractions far from 50% and generalize the result in terms of the geometry of the granular deposit.

DEM study of granular flow characteristics in the active and passive regions of a three‐dimensional rotating drum

“…Theoretical and analytical descriptions of the solid flow in the rotating drum have been adopted to understand the scaling relationship, granular flow behavior, and so on. In parallel, experimental approaches, such as radioactive particle tracking, high‐speed camera, positron emission particle tracking, and magnetic resonance imaging, have been employed to understand various phenomena like radial segregation, axial segregation, polydirectional stability, heat‐transfer behavior, intermittency, rheology transition, and axial dispersion in the rotating drum.…”

Controlling granular segregation using modulated flow

“…A stratum thinner than the flowing layer thickness, which is typically 5d to 10d, is unlikely to form since the stratum will be entrained into the flowing layer in the subsequent feed cycle and combine with the new stratum. Therefore, for low V tot , particles from more than one feed cycle end up merging into a single stratum, similar to the merging of streaks in modulated circular tumbler flow [38]. As a result, ∆H is greater than the value predicted by Eq.…”

“…In rotating tumblers under a periodic forcing protocol [35], phase lags between the external forcing and the response of granular flow occur, indicating a delayed response of the granular system to external excitation. The more complicated kinematics in unsteady flows of monodisperse particles suggest increased challenges in understanding and predicting segregation in unsteady bidisperse flows, but also a richer range of possibilities for mixing or segregation-induced pattern formation [18,37,38,39,40,41,42,43]. An example is the dynamics of segregation pattern formation in timeperiodic tumbler flow [37,38]: discrete streaks of small particles form instead of the typical semicircular segregated core of small particles that occurs for steady flow, and the properties of the streaks depend on the modulation scheme.…”

The tumbling mill rotation stability

“…In papers [2][3][4][5][6], the authors consider redistribution processes of the particles of the fill due to segregation associated with the complication of structure and the emergence of pattern formations with a loss of the motion stability.…”

“…In [4], the authors experimentally examined the effect of the emergence of a sinusoidal modulation of segregation zones in the cross-section of a chamber. They identified factors that influence the frequency and distribution of separation zones and mergers of groups of different particles.…”