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

Muite, B. K. and Hunt, M. L. and Joseph, G. G. (2004) The effects of a counter-current interstitial flow on a discharging hourglass. Physics of Fluids, 16 (9). pp. 3415-3425. ISSN 1070-6631. http://resolver.caltech.edu/CaltechAUTHORS:MUIpof04

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Abstract

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.


Item Type:Article
Additional Information:©2004 American Institute of Physics (Received 22 September 2003; accepted 17 June 2004; published online 2 August 2004) This work was supported by the National Science Foundation Grant Nos. CTS-9908430 and CTS-0314005 and Caltech’s Summer Undergraduate Research Fellowship. The authors thank Professor Ronald F. Scott for his helpful suggestions.
Subject Keywords:confined flow; granular flow; interstitials; viscosity; fluid oscillations; channel flow; flow visualisation
Record Number:CaltechAUTHORS:MUIpof04
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:MUIpof04
Alternative URL:http://dx.doi.org/10.1063/1.1781158
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1793
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:18 Feb 2006
Last Modified:26 Dec 2012 08:46

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