Collapse of quasi-two-dimensional wet granular columns

This paper deals with the experimental characterization of the collapse of wet granular columns in the pendular state, with the purpose of collecting data on triggering and jamming phenomena in wet granular media. The final deposit shape and the runout dynamics were studied for samples of glass beads, varying particle diameter, liquid surface tension, and liquid amount. We show how the runout distance decreases with increasing water amount (reaching a plateau for $w>1 \%$) and increases with increasing Bond number, while the top and toe angles and the final deposit height increase with increasing water amount and decrease with decreasing Bond number. Dimensional analysis allowed to discuss possible scalings for the runout length and the top and toe angles: a satisfying scaling was found, based on the combination of Bond number and liquid amount.Comment: 8 pages, 14 figure

formulation design and experiment interpretation through torque measurements in high shear wet granulation

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Shear-driven density segregation: an experimental study

Granular materials can segregate spontaneously due to differences in particle properties when subjected to vibrations, shear strain or because of the equipment geometries. Although the difference in particle size is the most critical factor that drives segregation, the effects of large density difference may also be detrimental for a lot of industries. In this work, we experimentally investigate density-driven segregation in bi-disperse mixtures of particles having the same size but different density when subjected to non-uniform shear rates. We found that the features of the segregation process are related to the density ratio as well as to the dimensionless loaded mass. The experimental outcomes are then compared with the solution of a simple density-driven segregation model. The model can successfully capture the main features of segregation driven by density for a range of density ratios

Shear-driven density segregation: an experimental study

Granular materials can segregate spontaneously due to differences in particle properties when subjected to vibrations, shear strain or because of the equipment geometries. Although the difference in particle size is the most critical factor that drives segregation, the effects of large density difference may also be detrimental for a lot of industries. In this work, we experimentally investigate density-driven segregation in bi-disperse mixtures of particles having the same size but different density when subjected to non-uniform shear rates. We found that the features of the segregation process are related to the density ratio as well as to the dimensionless loaded mass. The experimental outcomes are then compared with the solution of a simple density-driven segregation model. The model can successfully capture the main features of segregation driven by density for a range of density ratios

Scaling Laws for the Slip Velocity in Dense Granular Flows

none4In this Letter, the two-dimensional dense flow of polygonal particles on an incline with a flat frictional inferior boundary is analyzed by means of contact dynamics discrete element simulations, in order to develop boundary conditions for continuum models of dense granular flows. We show the evidence that the global slip phenomenon deviates significantly from simple sliding: a finite slip velocity is generally found for shear forces lower than the sliding threshold for particle-wall contacts. We determined simple scaling laws for the dependence of the slip velocity on shear rate, normal and shear stresses, and material parameters. The importance of a correct determination of the slip at the base of the incline, which is crucial for the calculation of flow rates, is discussed in relation to natural flows.mixedRiccardo Artoni;Andrea Santomaso;Massimiliano Go’;Paolo CanuArtoni, Riccardo; Santomaso, ANDREA CLAUDIO; Massimiliano, Go’; Canu, Paol

High shear granulation of crystalline sugars

Sugars can be used in granulation processes with different purposes: as diluents, binders, taste masking agents, sweeteners and agents for drug controlled release (e.g. sugar beads). They are soluble and sticky excipients and their processing in high shear granulators may be difficult: they can easily adhere to mixer walls or lead to uncontrolled granule growth. The purpose of this research was to evaluate the different behaviour in high shear wet granulation of four selected sugars: mannitol, sorbitol, xylitol and sucrose (size range of 60-300 \u3bcm). They were characterized by flowability and viscosity measurements and their solid state was studied by X-ray diffraction. Also the hygroscopicity was evaluated by conditioning powders at different relative humidity (RH 65 and 80%). Results highlighted that the humidity uptake did not produce changes in the solid state of the sugars but caused a reduction in flowability that was stronger in the case of sorbitol and xylitol. Powder flowability showed correlation to hygroscopicity but not to the final thickening of dissolved sugars. Granulation experiments demonstrated the feasibility of the process with the selected sugars and the possibility to predict the amount of water necessary to the process through mixer torque rheometer measurements