CFD analysis of power-law fluid flow and heat transfer around a confined semi-circular cylinder

Abstract

a b s t r a c tA numerical analysis using Ansys Fluent was carried out to investigate the forced convection of powerlaw fluids (power-law index varying from 0.2 to 1.8) around a heated semi-circular cylinder with wall confinement (or blockage ratio) of 25%, Prandtl number of 50, and Reynolds numbers 1-40. Flow and thermal fields were found to be steady for Re up to 40. The shear-thickening behavior was found to have a higher value of drag coefficient, whereas the shear-thinning behavior had a smaller value of drag coefficient when compared with Newtonian fluids in the steady regime. The wake size was found shorter in shear-thickening fluids than Newtonian and shear-thinning fluids. An overall heat transfer rate was calculated and found to increase with the rise in Reynolds number. The average Nusselt numbers were observed higher for shear-thinning fluids than Newtonian and shear-thickening fluids; and the maximum enhancement in the heat transfer was achieved approximately 47% as compared to Newtonian fluids. The present results have also been correlated in terms of wake length, drag coefficient and average Nusselt number expressions for various Reynolds numbers and power-law indices studied. In addition, the effects of blockage ratios ranging from 16.67% to 50% on the engineering output parameters with varying powerlaw index at Re = 40 were reported.

Effect of Fluid Yield Stress on Natural Convection From Horizontal Cylinders in a Square Enclosure

“…Broadly, for a given geometry, the shear-thinning fluid viscosity facilitates heat transfer over and above that in Newtonian fluids at fixed values of the Grashof and Prandtl numbers. This inference is also applicable to isolated cylinders of other shapes like square [15], triangular [16] Downloaded by [Australian National University] at 12:06 26 June 2016 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 4 and semi-circular [17] cross-sections, for instance. It is thus fair to say that adequate information is now available on the effect of power-law rheology on free-and forced convection heat transfer from variously shaped two-dimensional bluff bodies immersed in confined and unconfined fluid media, though this body of knowledge is neither as coherent nor as extensive as that for Newtonian media.…”

Fluid flow and heat transfer around a confined semi-circular cylinder: Onset of vortex shedding and effects of Reynolds and Prandtl numbers

“…In spite of such widespread applications, limited information is available in the open literature on the confined flow around and heat transfer from a semi-circular cylinder. We have recently systematically presented and discussed various studies on the flow and heat transfer characteristics in a channel with a built-in semi-circular cylinder [6][7][8]; Kumar and Dhiman [6] and Kumar et al [7] investigated the confined forced flow and heat transfer around a semi-circular cylinder, albeit at low Reynolds numbers (Re up to 40). This motivated us to examine the confined forced convection heat transfer from a semi-circular cylinder in the unsteady regime (or at intermediate Re).…”

Steady State Thermal Analysis of a Heat Sink with Rectangular Pin Fin

“…The result of the analysis showed that the pressure decreases along the fin length and maximum heat transfer takes place through the middle portion of the fin which is receiving maximum air flow [6]. The heat transfer correlations in the steady flow regime for the constant temperature and constant heat flux boundary conditions on the solid square cylinder in cross flow have been studies with cross flow placed symmetrically in a planar slit for a range of conditions [7]. CFD analysis has been performed by applying a load of 5 W to the heat sink and varied number of pin fins and found that on increasing total number of fins, the total heat transfer rate also increases [8].…”