Influence of power-law index on transitional Reynolds numbers for flow over a semi-circular cylinder

In this work, the governing partial differential equations (continuity and Cauchy’s momentum equations) describing the flow of power-law type non-Newtonian fluids across a semi-circular cylinder (oriented with its curved surface in the upstream direction) have been solved numerically. In particular,...

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Bibliographic Details
Published in:Applied mathematical modelling 2011-12, Vol.35 (12), p.5766-5785
Main Authors: Chandra, Avinash, Chhabra, R.P.
Format: Article
Language:English
Subjects:
Boundary layer and shear turbulence
Computational fluid dynamics
Computational methods in fluid dynamics
Critical Reynolds number
Cylinders
Exact sciences and technology
Flow separation
Fluid dynamics
Fluid flow
Fluids
Fundamental areas of phenomenology (including applications)
Laminar
Mathematical models
Physics
Power-law fluids
Reynolds number
Rotational flow and vorticity
Semi-circular cylinder
Strouhal number
Turbulent flows, convection, and heat transfer
Vortex shedding
Wakes
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Summary:In this work, the governing partial differential equations (continuity and Cauchy’s momentum equations) describing the flow of power-law type non-Newtonian fluids across a semi-circular cylinder (oriented with its curved surface in the upstream direction) have been solved numerically. In particular, consideration has been given to the delineation of the critical Reynolds numbers denoting the onset of flow separation from the surface of the cylinder and the onset of the laminar vortex shedding regime. This information is germane to establish the scaling of the macroscopic characteristics like drag coefficient and Strouhal number on the governing parameters, namely, Reynolds number and power-law index. The present results clearly suggest that the transitional Reynolds numbers show a strong dependence on the type (shear-thinning and shear-thickening) of fluid behavior as well as on the severity of the shear-dependence of the viscosity. With reference to the behavior seen in Newtonian fluids, the flow remains not only attached to the surface up to higher Reynolds numbers, but shear-thinning behavior also delays the onset of the laminar vortex shedding regime. As expected, shear-thickening fluids, of course, display the opposite characteristics.
ISSN:0307-904X
DOI:10.1016/j.apm.2011.05.004