Effect of Non-Newtonian Rheology on Heat Transfer from a Square Cylinder in Unsteady Flow Regime
Akhilesh K. Sahu1,a, Raj P. Chhabra1,b and V. Eswaran2
Department of Chemical Engineering, IIT Kanpur, Kanpur 208 016, India.
aakhilesh@iitk.ac.in
bchhabra@iitk.ac.in
Department of Mechanical Engineering, IIT Kanpur, Kanpur 208 016, India.
eswar@iitk.ac.in
ABSTRACT
The flow and forced convection heat transfer characteristics of an isolated square cylinder in power law fluids are numerically investigated for the unsteady periodic laminar flow regime. The semi-explicit finite volume method has been used on a non-uniform collocated grid arrangement to solve the governing equations for the following ranges of conditions 60 ≤ Re ≤ 160, 0.7 ≤ Pr ≤ 50 and 0.5 ≤ n ≤ 1.8. The variation of the time averaged local Nusselt number over each face of the cylinder, representative isotherm contour plots and variation of Nusselt number with time are presented to elucidate the role of Prandtl number, Reynolds number and power law index (n) on momentum and heat transfer characteristics. The results show that in power law fluids (n > 1 and n < 1), the Nusselt number of the cylinder increases with Reynolds and/or Prandtl number. A heat transfer correlation is presented to estimate the value of heat transfer coefficient in the above stated range of conditions.
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