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- Title
Influence of bubbles characteristics on the skin friction and velocity gradient on solid sphere.
- Authors
Essadki, A. H.; Nikov, I.; Delmas, H.
- Abstract
A detailed study of the effects of individual bubbles at high gas flow-rate has shown, that the dominant influence on skin friction over a solid sphere is the bubble volume in compared to bubble frequency. Nevertheless the bubble frequency is very important in case of low gas flow-rate. Referring to bubbles produced by a gas distributor, statistical and spectral analyses were performed to study the influence of bubbling on exposure time and magnitude of fluctuations. Referring to a calibrated bubble train, the existence of critical frequency is demonstrated. A bubble with larger volume and a mobile, oscillatory surface generates larger velocity gradient. In the case of gas distribution, histograms of the velocity gradient for a 2 mm glass sphere creating bubble coalescence reveal the maximum exceeds 48 000 s−1 in the front zone and 2000 s−1 in the rear zone ( θ = 180°). For 5 mm plastic spheres creating bubble break-up, the maximum of the velocity gradient is only 8100 s−1 for the front part of the sphere and 2000 s−1 in the rear zone.
- Subjects
BUBBLES; GAS flow; FRICTION; STATISTICS; SPECTRUM analysis; GAS distribution
- Publication
Canadian Journal of Chemical Engineering, 2011, Vol 89, Issue 6, p1358
- ISSN
0008-4034
- Publication type
Article
- DOI
10.1002/cjce.20647