Drag of a dispersion of nonhomogeneously structured flocs in a flow field
Resource
Journal of Colloid and Interface Science 284 (1): 332-338
Journal
Journal of Colloid and Interface Science
Journal Volume
284
Journal Issue
1
Pages
332-338
Date Issued
2005
Date
2005
Author(s)
Abstract
The influence of floc structure and floc concentration on the drag acting on a floc is investigated theoretically. A two-layer model is adopted to describe floc structure, and a cell model is used to simulate a floc dispersion. The influences of the key parameters of the problem under consideration, including floc concentration, Reynolds number, the ratio (permeability of outer layer/permeability of inner layer), and the ratio (thickness of outer layer/thickness of inner layer), on the drag coefficient are discussed. We show that the more heterogeneous the floc structure is, the greater the drag and the more significant the deviation of curve of variation of drag coefficient against Reynolds number from a Stokes-law-like relation. The drag on a floc declines with the decrease in floc concentration, and, due to the convective flow of the fluid, the distortion of streamlines surrounding a floc becomes more serious and the deviation of the variation of the curve of drag against Reynolds number from a Stokes-law-like relation is more significant.
Type
journal article
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