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Modelling and experiments of wet granular flows in rotating drums

Tuesday 6th January 2009 - 15:15 to 15:40
INI Seminar Room 1
In addition to its wide usage in industry as mixers and kilns, rotating drums partially filled with granular materials is a prototypical systems for studying fundamentals of dynamics and mixing in dense granular flows. This study incorporates pendular liquid-bridge forces into a nonlinear soft-sphere discrete element method (DEM) to investigate the behavior of wet granular materials in rotating drums under the rolling flow regime. Simulations with two- and three-dimensional flow fields are compared and the importance of three-dimensional effects are evaluated. Simulated results, including the dynamic angle of repose and the time-averaged velocity profiles at the bed surface and along the bed depth, are validated against a series of experiments based on application of particle image velocimetery (PIV) to a quasi-two dimensional (i.d.120mm×10mm) rotating tumbler. The roles of rolling and sliding frictions are compared, and a model of resistance to rolling is developed for a better prediction of granular velocity. Particularly, the influence of dimensionless liquid bridge volume on behavior of wet granular materials in both the active layer and the plug-flow region is investigated.

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University of Cambridge Research Councils UK
    Clay Mathematics Institute London Mathematical Society NM Rothschild and Sons