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Effect of temperature-dependent viscosity on forced convection heat transfer from a cylinder in crossflow of power-law fluids. (English) Zbl 1197.80028
Summary: The steady, two-dimensional and incompressible flow of power-law fluids across an unconfined isothermal heated circular cylinder is investigated numerically to ascertain the effect of temperature-dependent viscosity on the flow and forced convection heat transfer phenomena. Extensive numerical results elucidating the variation of the heat transfer characteristics and drag coefficient on the severity of temperature dependence of viscosity ($$0 \leqslant b \leqslant 0.5$$), power law index ($$0.6 \leqslant n \leqslant 1.6$$), Prandtl number ($$1 \leqslant Pr \leqslant 100$$) and Reynolds number ($$1 \leqslant Re \leqslant 30$$) are presented. The coupled momentum and energy equations are expressed in the stream function/vorticity formulation and solved using a second-order accurate finite difference method to determine the local and surface-averaged Nusselt numbers, the drag coefficient, and to map the flow domain in terms of the temperature and flow fields near the cylinder. The variation of viscosity with temperature is shown to have a substantial effect on both the local and surface-averaged values of the Nusselt number. As expected, the results also suggest that the rate of heat transfer shows positive dependence on the Reynolds number and Prandtl number. Furthermore, stronger the dependence of viscosity on the temperature, the greater is the enhancement in the rate of heat transfer. Finally, all else being equal, shear-thinning fluid behaviour facilitates heat transfer while the shear-thickening behaviour has deleterious effect on heat transfer.

##### MSC:
 80A20 Heat and mass transfer, heat flow (MSC2010) 76R05 Forced convection 76A05 Non-Newtonian fluids 76M20 Finite difference methods applied to problems in fluid mechanics 80M20 Finite difference methods applied to problems in thermodynamics and heat transfer
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