Stokes’s Cradle: Newton’s Cradle with Liquid Coating

Donahue, Carly M.; Hrenya, Christine M.; Davis, Robert H.

doi:10.1103/physrevlett.105.034501

Cited by 39 publications

(27 citation statements)

References 18 publications

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“…However, we found the inclusion of string tension critical to predicting the correct outcomes and trends since the particles rotate through a significant angle before deagglomerating, allowing for large string tension forces to act over a long period of time. Finally, based on recent experimental evidence [10], we do not presume cavitation upon rebound precludes resistance and instead include the effect of fluid resistance.…”

Section: Theory Descriptionmentioning

confidence: 99%

Mechanisms for agglomeration and deagglomeration following oblique collisions of wet particles

et al. 2012

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Previous studies on wetted, particle-particle collisions have been limited to head-on collisions, but in many-particle flows, collisions are inherently oblique. In this work, we explore such oblique collisions experimentally and theoretically. Whereas in normal collisions particles rebound only due to solid deformation, we observe in oblique collisions a new outcome where the particles initially form a rotating doublet and then deagglomerate at a later time due to so-called centrifugal forces. Surprisingly, we discover the essential role of capillary forces in oblique collisions even when the capillary number (viscous over capillary forces) is high. This recognition leads to the introduction of a dimensionless number, the centrifugal number (centrifugal over capillary forces), which together with the previously established Stokes number characterizes the regime map of outcomes. Unexpectedly, we observe a normal restitution coefficient greater than unity at large impact angles, the mechanism for which may also be observed in other agglomerating systems.

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Section: Theory Descriptionmentioning

confidence: 99%

Mechanisms for agglomeration and deagglomeration following oblique collisions of wet particles

et al. 2012

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“…Antonyuk et al [24] demonstrated that the energy loss caused by the viscous damping force and drag force are more significant than other factors in the energy dissipation process. Recently, the Hrenya group from Colorado University has undertaken much work to characterize the collision mechanics in the presence of liquid: Donahue et al [25,26] developed a scaling theory to characterize the three-body collision that considers liquid bridge force existing between agglomerating particles initially and pressure dependence in the liquid viscosity. In another paper, they explored particle-particle oblique collisions and observed a rotating doublet for two obliquely colliding particles before deagglomeration.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of oblique impact between dry spheres and liquid layers

Liu

Chen

2013

Phys. Rev. E

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Liquid addition is common in industrial fluidization-based processes. A detailed understanding of collision mechanics of particles with liquid layers is helpful to optimize these processes. The normal impact with liquid has been studied extensively; however, the studies on oblique impact with liquid are scarce. In this work, experiments are conducted to trace Al_{2}O_{3} spheres obliquely impacting on a surface covered by liquid layers, in which the free-fall spheres are disturbed initially by a horizontal gas flow. The oblique impact exhibits different rebound behaviors from normal collision due to the occurrence of strong rotation. The normal and tangential restitution coefficients (e_{n} and e_{t}) and liquid bridge rupture time (t_{rup}) are analyzed. With increase in liquid layer thickness and viscosity, e_{n} and e_{t} decline, and t_{rup} increases. With increase in tangential velocity, e_{t} decreases first and then increases, whereas e_{n} remains nearly unchanged, and t_{rup} decreases constantly. A modified Stokes number is proposed to further explore the relation between restitution coefficients and the impact parameters. Finally, an analysis of energy dissipation shows that the contact deformation and liquid phase are the two main sources of total energy dissipation. Unexpectedly, the dissipative energy caused by the liquid phase is independent of tangential velocity.

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“…For normal collisions, de-agglomeration or rebound of colliding particles occurs for values of St n greater than a critical Stokes number, namely St * n . The value of St * n can be determined either empirically via experiments or theoretically by considering the properties of both the fluid and the solid particles (Ennis, Tardos & Pfeffer 1991;Davis, Rager & Good 2002;Donahue, Hrenya & Davis 2010a). Recent experiments on normal collisions between a particle and a wetted wall have verified the lubrication force for St n < St * n (Marston, Wong & Thoroddsen 2010).…”

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confidence: 96%

Agglomeration and de-agglomeration of rotating wet doublets

et al. 2012

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In this work, experiments using a pendulum apparatus were conducted for two particles engaged in oblique, wetted collisions over a range of impact angles, impact velocities, coating thicknesses, liquid viscosities, particle materials, and particle radii. From previous studies on normal or head-on collisions, the two particles bounce apart if the Stokes number (a ratio of particle inertia to viscous forces) exceeds a critical value, whereas they stick together if the Stokes number is below this critical value. However, for oblique collisions, an additional outcome is observed at moderate Stokes numbers and impact angles, in which the spheres initially stick together, rotate as a doublet, and then separate due to centrifugal forces. We refer to this outcome as 'stick-rotate-separate'. For subcritical Stokes numbers exhibiting this new outcome, the experimental results for the apparent coefficient of normal restitution and angle of rotation from impact to separation show only weak dependence on the fluid viscosity and thickness and the dry restitution coefficient, whereas they both decrease with increasing particle radius. These results are in contrast with those for supercritical Stokes numbers in which the spheres bounce upon impact. An accompanying theory based on lubrication forces, the glass transition of the liquid layer, and solid deformation and rebound agrees well with experimental results and gives insight into the observed trends.

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Stokes’s Cradle: Newton’s Cradle with Liquid Coating

Cited by 39 publications

References 18 publications

Mechanisms for agglomeration and deagglomeration following oblique collisions of wet particles

Mechanisms for agglomeration and deagglomeration following oblique collisions of wet particles

Experimental study of oblique impact between dry spheres and liquid layers

Agglomeration and de-agglomeration of rotating wet doublets

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