Analysis of the Effect of Periodic Magnetic Field, Heat Absorption/Generation and Aspect Ratio of the Enclosure on Non-Newtonian Natural Convection

Document Type : Full Lenght Research Article

Authors

1 Department of Mechanical Engineering, Yazd University

2 Faculty of Mechanical Engineering, University of Kashan,

Abstract

In the numerical present study, MHD natural convection heat transfer of non-Newtonian power-law fluid in a two-dimensional enclosure with variable aspect ratio in the presence of heat absorption/generation is investigated by using the lattice Boltzmann method (LBM). The magnetic field is applied to the enclosure in uniform and periodic forms. The vertical wall and curved walls of the enclosure are at constant hot and cold temperature, respectively. The present work is validated with previous studies and the accuracy of the results is ensured. The effect of the Hartmann number, non-Newtonian power-law index, heat absorption/generation coefficient, aspect ratio of the enclosure and the type of magnetic field applied on the nature of flow and heat transfer are studied. The results show that increasing the non-Newtonian power-law index, Hartmann number and the heat absorption/generation coefficient reduce the Nusselt number. By increasing the heat generation/absorption coefficient, aspect ratio and decreasing the non-Newtonian power-law index, the effect of the magnetic field increases. Applying a magnetic field periodically compared to a uniform form leads to an increase of in Nusselt number and flow strength that this effect is greatest for shear thinning fluid and negligible for shear thickening fluid. Increase of Hartmann number and heat absorption/generation coefficient simultaneous leads to further decrease of average Nusselt number. This research can be helpful in the optimal design of heat transfer equipment.

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Articles in Press, Accepted Manuscript
Available Online from 17 June 2021
  • Receive Date: 27 December 2020
  • Revise Date: 16 June 2021
  • Accept Date: 17 June 2021