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Size segregation in granular fluid flows

Friday 9th January 2009 - 14:00 to 14:25
INI Seminar Room 1
Particle segregation has important implications both for natural phenomena and industrial activities, inducing important effects on the rheology of the mixture and on transport dynamics. Despite the importance of particle segregation, the theoretical framework developed for the description of this phenomenon is still incomplete. For these reasons, the present contribution is aimed at the presentation of the development of a flow model, based on the mass balance of the particles coupled with the momentum balance of fluid and sediments, in order to describe in a realistic way segregation phenomena that are important in environmental problems, such as debris flow or wind blown sand. We focus on steady fully developed flows of a mixture of water and spherical particles of two different sizes made of the same material. The hyrodynamic model is an evolution of that employed by Jenkins and Hanes (J. Fluid Mech. 370, 29-53, 1998) and the segregation model is that introduced by Arnarson and Jenkids (Phys. Fluids 16, 4543-4550, 2004). We consider flows down inclines that are driven both by gravity and the shear stress of a clear turbulent fluid above the particles. We take the fluid to be either air or water. Profiles of mixture volume fraction, particle velocity, fluid velocity, and species volume fraction are predicted and, where possible, compared to experimental measurements.
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University of Cambridge Research Councils UK
    Clay Mathematics Institute London Mathematical Society NM Rothschild and Sons