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Heat transfer in differentially heated non-newtonian cavities

Heat transfer in differentially heated non-newtonian cavities

Pericleous, K.A. ORCID: 0000-0002-7426-9999 (1994) Heat transfer in differentially heated non-newtonian cavities. International Journal of Numerical Methods for Heat and Fluid Flow, 4 (3). pp. 229-248. ISSN 0961-5539 (doi:10.1108/EUM0000000004040)

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Abstract

The flow development and heat transfer in a differentially heated cavity containing a non-Newtonian fluid is studied using CFD techniques. Investigations are made for a fluid obeying a power-law type behaviour, for a nominal Rayleigh number of 105. Both dilatant and pseudoplastic regimes are considered and the Nusselt number is obtained for a range of power-law index values. The results, given in a graphical and tabular form, suggest that deviations from Newtonian stress-strain behaviour can lead to large changes in overall heat transfer. These changes are due to the behaviour of the wall boundary layers. In the dilatant, or shear-thickening regime, the isothermal wall layers are thick and slow-moving; as a consequence, buoyancy induced flow affects the whole of the cavity volume. In contrast, the pseudoplastic (or shear-thinning) regime leads to thin, fast-moving wall layers whose effect does not propagate to the core of the cavity which remains stagnant. This behaviour, which is directly attributable to the local value of the fluid viscosity, causes the average Nusselt number to decrease with the power-law index, n. Pseudoplastic fluids are therefore better at conducting heat than Newtonian fluids, and conversely dilatant fluids are worse. The information contained in this paper is of general interest to workers in heat transfer, but is more specifically relevant to researchers in non-Newtonian fluids. Example applications include biotechnology, where close temperature control of bio-cultures in enclosed vessels is required, the food processing industry, the metals casting industry and areas where heat transfer in fine suspensions is required.

Item Type: Article
Uncontrolled Keywords: heat transfer, non-Newtonian flow, CFD, Computational Fluid Dynamics, natural convection, cavity flow, power-law fluids
Subjects: Q Science > QA Mathematics > QA76 Computer software
Q Science > QC Physics
Pre-2014 Departments: School of Computing & Mathematical Sciences
School of Computing & Mathematical Sciences > Centre for Numerical Modelling & Process Analysis > Computational Science & Engineering Group
Related URLs:
Last Modified: 14 Oct 2016 09:15
Selected for GREAT 2016: None
Selected for GREAT 2017: None
Selected for GREAT 2018: None
URI: http://gala.gre.ac.uk/id/eprint/5960

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