Effect of Horizontal Spacing on Natural Convection to Power-Law Fluids from Two Horizontally Aligned Cylinders

Abstract

This paper expounds the effect of horizontal spacing between two horizontally aligned circular cylinders on laminar natural convection to non-Newtonian power-law fluids. Numerical computations have been carried out for the following range of conditions: Grashof number (10 to 10⁵), Prandtl number (0.71 to 100), horizontal spacing (0 to 20 times the cylinder diameter), and power-law index (0.4 to 1.6). The flow, pressure, and thermal fields are pictorially visualized in terms of streamlines, pressure contours, and temperature contours, respectively. The average Nusselt number shows a positive reliance on both Grashof and Prandtl numbers, whereas an adverse dependence is observed on power-law index. Irrespective of all other parameters, shear-thinning fluid behavior is seen to promote the convection, whereas shear-thickening behavior impedes it with reference to the Newtonian fluid. With decrease in the horizontal spacing, the average Nusselt number increases and attains a maximum value corresponding to the optimal spacing, however, it diminishes greatly with further reduction in spacing. Furthermore, the average Nusselt number is in excess of 21-89% at the optimal spacing compared to no-spacing. Finally, this paper is concluded with producing a new correlation for the average Nusselt number.

Additional information

Notes on contributors

Subhasisa Rath

Subhasisa Rath is a Ph.D. research scholar in the School of Energy Science and Engineering, Indian Institute of Technology Kharagpur, India. He received his B.Tech. degree in Mechanical Engineering from Biju Patnaik University of Technology, Odisha, India in 2012, and M.Tech. degree from Siksha ‘O’ Anusandhan University, Bhubaneswar, India in 2015. He was awarded the “University Gold Medal” in 2017 for outstanding academic performance in his Masters. His doctoral research is primarily focused on computational fluid dynamics study of laminar and turbulent natural convection in Newtonian and non-Newtonian fluid mediums. ORCID ID: https://orcid.org/0000-0002-4202-7434

Sukanta Kumar Dash

Sukanta Kumar Dash is a Professor in the Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, India. He received his Ph.D. degree from the Indian Institute of Technology Kharagpur, India in 1989. He worked as a scientist in CMERI, Durgapur, India from 1989-93, and as a Research Manager in R&D Division in Tata Steel, Jamshedpur, India, from 1995-98. He has published more than 80 international scientific papers. He was awarded the “Alexander-von-Humboldt” research fellowship in 1993. His research interests include computational fluid mechanics and heat transfer, natural convection, free surface flow, and two-phase flow.