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Physics of Fluids / Volume 16 / Issue 9 / ARTICLES

Phys. Fluids 16, 3415 (2004); doi:10.1063/1.1781158 (11 pages)

The effects of a counter-current interstitial flow on a discharging hourglass

B. K. Muite, M. L. Hunt, and G. G. Joseph

Division of Engineering and Applied Science, California Institute of Technology, MS 104-44, Pasadena, California 91125

(Received 22 September 2003; accepted 17 June 2004; published online 2 August 2004)

This work experimentally investigates the effects of an interstitial fluid on the discharge of granular material within an hourglass. The experiments include observations of the flow patterns, measurements of the discharge rates, and pressure variations for a range of different fluid viscosities, particle densities and diameters, and hourglass geometries. The results are classified into three regimes: (i) granular flows with negligible interstitial fluid effects; (ii) flows affected by the presence of the interstitial fluid; and (iii) a no-flow region in which particles arch across the orifice and do not discharge. Within the fluid-affected region, the flows were visually classified as lubricated and air-coupled flows, oscillatory flows, channeling flows in which the flow preferentially rises along the sidewalls, and fluidized flows in which the upward flow suspends the particles. The discharge rates depends on the Archimedes number, the ratio of the effective hopper diameter to the particle diameter, and hourglass geometry. The hopper-discharge experiments, as well as experiments found in the literature, demonstrate that the presence of the interstitial fluid is important when the nondimensional ratio (N) of the single-particle terminal velocity to the hopper discharge velocity is less than 10. Flow ceased in all experiments in which the particle diameter was greater than 25% of the effective hopper diameter regardless of the interstitial fluid.

© 2004 American Institute of Physics

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KEYWORDS and PACS

Keywords

confined flow, granular flow, interstitials, viscosity, fluid oscillations, channel flow, flow visualisation

PACS

  • 47.60.-i

    Flow phenomena in quasi-one-dimensional systems

  • 47.55.Kf

    Particle-laden flows

  • 47.35.-i

    Hydrodynamic waves

  • 47.80.-v

    Instrumentation and measurement methods in fluid dynamics

ARTICLE DATA

Permalink
http://link.aip.org/link/doi/10.1063/1.1781158

PUBLICATION DATA

ISSN:

1070-6631 (print)  
1089-7666 (online)

Publisher:

$abstract.society.value is a Member of CrossRef American Institute of Physics

For access to fully linked references, you need to log in.
    X. Wu, K. J. Måløy, A. Hansen, M. Ammi, and D. Bideau, "Why hour glasses tick," Phys. Rev. Lett. 71, 1363 (1993).

    T. Le Pennec, K. J. Måløy, A. Hansen, M. Ammi, D. Bideau, and X. Wu, "Ticking hour glasses: Experimental analysis of intermittent flow," Phys. Rev. E 53, 2257 (1996).

    E. S.G. Shaqfeh and A. Acrivos, "Enhanced sedimentation in vessels with inclined walls: Experimental observations," Phys. Fluids 30, 1905 (1987)PFLDAS000030000007001905000001.


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