Particle segregation is common in natural and industrial processes involving flowing granular materials. Complex, and seemingly contradictory, segregation phenomena have been observed for different boundary conditions and forcing. Using discrete element method simulations, we show that segregation of a single particle intruder can be described in a unified manner across different flow configurations. A scaling relation for the net segregation force is obtained by measuring forces on an intruder particle in controlledvelocity flows where gravity and flow kinematics are varied independently. The scaling law consists of two additive terms: a buoyancylike gravityinduced pressure gradient term and a shear rate gradient term, both of which depend on the particle size ratio. The shear rate gradient term reflects a kinematicsdriven mechanism whereby larger (smaller) intruders are pushed toward higher (lower) shear rate regions. The scaling is validated, without refitting, in walldriven flows, inclined walldriven flows, vertical silo flows, and freesurface flows down inclines. Comparing the segregation force with the intruder weight results in predictions of the segregation direction that match experimental and computational results for various flow configurations.
Exploring shearinduced segregation in controlledvelocity granular flows
Particle segregation in geophysical and industrial granular flows is typically driven by gravity and shear. While gravityinduced segregation is relatively well understood, shearinduced segregation is not. In particular, what controls segregation in the absence of gravity and the interplay between shearand gravitydriven segregation remain unclear. Here, we explore the shearinduced segregation force on an intruder particle in controlledvelocity granular flows where the shear profile is systematically varied. The shearinduced segregation force is found to be proportional to the shear rate gradient, which effectively pushes the large intruder from lower to higher shear rate regions. A scaling law is developed for the segregation force that is accurate over a wide range of overburden pressures and shear rates, and hence inertial numbers.
 Editors:
 Aguirre, M.A.; Luding, S.; Pugnaloni, L.A.; Soto, R.
 Award ID(s):
 1929265
 Publication Date:
 NSFPAR ID:
 10289666
 Journal Name:
 EPJ Web of Conferences
 Volume:
 249
 Page Range or eLocationID:
 03012
 ISSN:
 2100014X
 Sponsoring Org:
 National Science Foundation
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