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Sedimentation and sediment flow in settling tanks with inclined walls

Published online by Cambridge University Press:  26 April 2006

B. Kapoor  and
A. Acrivos
B. Kapoor
Affiliation:
The Levich Institute, The City College of the City University of New York, New York, NY 10031, USA Present address: Molten Metal Technology, Inc., 51 Sawyer Rd, Waltham, MA 02154, USA
A. Acrivos
Affiliation:
The Levich Institute, The City College of the City University of New York, New York, NY 10031, USA
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Abstract

The flow of a sediment layer that forms on an inclined plate as a consequence of the steady sedimentation of spherical particles was investigated theoretically as well as experimentally. The theoretical analysis was based on the model proposed by Nir & Acrivos (1990), modified to include shear-induced diffusion due to gradients in the shear stress as well as a slip velocity along the wall due to the finite size of the particles. The resulting set of partial differential equations, which is amenable to a similarity-type solution both near the leading edge as well as far downstream, was solved numerically using a finite difference scheme thereby yielding theoretical predictions for the particle concentration and velocity profiles, plus the local sediment layer thickness, all along the plate. In addition, a new experimental technique based on laser Doppler anemometry was developed and was used to measure the particle velocity profiles in the highly concentrated sediment layer as well as the corresponding slip coefficient which relates the slip velocity to the velocity gradient adjacent to a wall. The thickness profile of the sediment layer was also measured experimentally by means of video imaging. It was found that the experimental results thus obtained for the particle velocity profile and for the local sediment layer thickness were in very good agreement with the corresponding theoretical predictions especially considering that the latter did not make use of any adjustable parameters.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 290 , 10 May 1995 , pp. 39 - 66
Copyright
© 1995 Cambridge University Press

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