Atapattu, D. D. ; Chhabra, R. P. ; Uhlherr, P. H. T. (1990) Wall effect for spheres falling at small reynolds number in a viscoplastic medium Journal of Non-Newtonian Fluid Mechanics, 38 (1). pp. 31-42. ISSN 0377-0257
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Official URL: http://www.sciencedirect.com/science/article/pii/0...
Related URL: http://dx.doi.org/10.1016/0377-0257(90)85031-S
Abstract
The wall factor, f = u/u∞, for spheres falling slowly under gravity through viscoplastic media has been measured. A critical value of sphere-to-tube diameter ratio, (d/D)crit, is found to exist, below which no wall effect is descernible, f = 1. The critical diameter ratio is correlated in terms of a dimensionless yield-gravity group Y = τy/gd(ϱs-ϱ); it appears to be related to the dimensions of the sheared fluid envelope surrounding the sphere. For diameter ratios larger than the critical value, the behaviour of the wall factor is very similar to that found for shear-thinning fluids without yield stress.
| Item Type: | Article |
|---|---|
| Source: | Copyright of this article belongs to Elsevier Science. |
| Keywords: | Creeping Motion; Sphere Motion; Viscoplastic Medium; Wall Effect |
| ID Code: | 78630 |
| Deposited On: | 20 Jan 2012 11:45 |
| Last Modified: | 20 Jan 2012 11:45 |
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