Unsteady buoyant convection of nanofluid in a porous annulus: impacts of size and location of thermal source–sink pairs

Abstract

The current numerical investigation deals with natural convection in a nanofluid-saturated porous cylindrical annulus subjected to partial heating and cooling of side walls by adopting Brinkman-extended Darcy Model to govern the fluid flow in porous media. By choosing five different locations and four lengths of thermal source–sink pairs, the impact of discrete heating–cooling on fluid flow, thermal transport rates and thermal mixing in a porous annular enclosure has been addressed. From the vast range of numerical simulations, the results provide information on the proper size and location of source–sink combinations to dissipate maximum thermal transport along with better thermal mixing in the enclosure. The importance of porosity, nanoparticle concentration, Darcy and Rayleigh numbers on overall thermal dissipation rate has also been discussed. The results showed that identifying an optimum source–sink location along with an appropriate choice of other control parameters can lead to higher thermal transport enhancement and thermal mixing.

KEYWORDS:

• Annulus
• discrete heating
• nanofluids
• natural convection
• porous medium

Acknowledgements

The authors acknowledge the respective universities for their support and encouragement. NKR acknowledges the support from the Ulsan National Institute of Science and Technology, Republic of Korea. HAKS sincerely acknowledges the CMR Institute of Technology, Bengaluru, India, for the constant support and encouragement. MS acknowledges the support from UTAS, Ibri, Oman, under the Internal Research Funding via Project No. DSR-IRPS-2021-22-PROP-1.

Author contributions

Identification of problem – MS. Performing numerical simulations and graph plotting – NKR. Paper writing – NKR & HAKS. Proofread and overall preparation– MS & RS.