CFD study of heat transfer in power-law fluids over a corrugated cylinder

Abstract

The computational study of power-law fluid flow, along with heat transfer attributes over a corrugated heated cylinder, is explored using ANSYS FLUENT (Version 18.0). Fluids power-law indices fall in the range of 0.25 ≤ n ≤ 1.5, and the Reynolds number spans in the range of 1 ≤ Re_N ≤ 40. The flow is two-dimensional, steady, and laminar. A wide range of Prandtl numbers (0.7 ≤ Pr_N ≤ 500) is used to cover the most industrially applied fluids. A domain height of 135D_h is used. A grid with the smallest element size of 0.04 m and 135,914 nodes was used. Flow and heat transfer attributes were studied using streamlines, isotherms, and local and average Nusselt numbers. The average Nusselt number increases with Re_N and/or Pr_N. The heat transfer rate is significantly lower in dilatant fluids and higher in pseudoplastic fluids than in Newtonian fluids. The onset of wake formation behind the cylinder takes place at Re_N = 10. The increase in Reynolds number (Re_N) and power-law index (n) causes an increase in wake size. Heat transfer increases with the Reynolds number and/or decrease in the power-law index. The enhancement in heat transfer due to corrugation is studied in detail in terms of average Nusselt number, which has not been studied for arched corrugated cylinder, even for Newtonian fluids in low Reynolds number range. A Nusselt number correlation is also developed for the given ranges of conditions.