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Axial dispersion in weakly turbulent flows of yield stress fluids
- Source :
- Journal of Non-Newtonian Fluid Mechanics. 235:1-19
- Publication Year :
- 2016
- Publisher :
- Elsevier BV, 2016.
-
Abstract
- We analyze turbulent flows of shear-thinning yield stress fluids in both pipe and channel geometries. We lay down a consistent procedure for hydraulic calculation of Herschel-Bulkley fluids; i.e. finding the relationship between the mean velocity and the wall shear stress. We show that for weakly turbulent flows it is necessary to include an analysis of wall layers in studying dispersion. In pipe flows, we observe an O ( 10 ) increase in Taylor dispersion coefficients, compared to highly turbulent values. This arises from a combination of large velocity and small turbulent dispersivity, acting over a wall layer that can represent ≳ 20% of the pipe area. In channel flows the wall layer effect is more modest, but still represents an O ( 1 ) increase in Taylor dispersion coefficient. The preceding effects are negated for small power law index, due to rapid reduction of the wall layer, and are observed to reduce modestly as the yield stress increases.
- Subjects :
- Materials science
Turbulence
Applied Mathematics
Mechanical Engineering
General Chemical Engineering
Taylor dispersion
02 engineering and technology
Mechanics
Condensed Matter Physics
01 natural sciences
Power law
010305 fluids & plasmas
Physics::Fluid Dynamics
020401 chemical engineering
0103 physical sciences
Dispersion (optics)
Shear stress
General Materials Science
0204 chemical engineering
Subjects
Details
- ISSN :
- 03770257
- Volume :
- 235
- Database :
- OpenAIRE
- Journal :
- Journal of Non-Newtonian Fluid Mechanics
- Accession number :
- edsair.doi...........b468d89e550960e70774e2bd21ba590d