Modeling the Collisional-Plastic Stress Transition for Bin Discharge of Granular Material
We propose a heuristic model for the transition between collisional and frictional/plastic stresses in the flowof granular material. Our approach is based on a physically motivated, nonlinear ‘blending’ function that produces aweighted average of the limiting stresses, depending on the local void fraction in the flow field. Previously publishedstress models are utilized to describe the behavior in the collisional (Lun et al., 1984) and quasi-static limits (Schaeffer,1987 and Syamlal et al., 1993). Sigmoidal and hyperbolic tangent functions are used to mimic the observed smooth yetrapid transition between the collisional and plastic stress zones. We implement our stress transition model in an opensourcemultiphase flow solver, MFIX (Multiphase Flow with Interphase eXchanges, www.mfix.org) and demonstrate itsapplication to a standard bin discharge problem. The model’s effectiveness is illustrated by comparing computationalpredictions to the experimentally derived Beverloo correlation. With the correct choice of function parameters, themodel predicts bin discharge rates within the error margins of the Beverloo correlation and is more accurate than one ofthe alternative granular stress models proposed in the literature. Although a second granular stress model in the literatureis also reasonably consistent with the Beverloo correlation, we propose that our alternative blending function is likely tobe more adaptable to situations with more complex solids properties (e.g., ‘sticky’ solids).
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 964721
- Resource Relation:
- Conference: Powders and Grains 2009 - Golden, Colorado, United States of America - 7/14/2009 12:00:00 AM-
- Country of Publication:
- United States
- Language:
- English
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