Free convective heat transfer efficiency in Al2O3–Cu/water hybrid nanofluid inside a rectotrapezoidal enclosure

Mohammad M. Rahman, Ziad Saghir, Ioan Pop*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


Purpose: This paper aims to investigate numerically the free convective heat transfer efficiency inside a rectotrapezoidal enclosure filled with Al2O3–Cu/water hybrid fluid. The bottom wall of the cavity is uniformly heated, the upper horizontal wall is insulated, and the remaining walls are considered cold. A new thermophysical relation determining the thermal conductivity of the hybrid nanofluid has been established, which produced results those match with experimental ones. Design/methodology/approach: The governing partial differential equations are solved using the finite element method of Galerkin type. The simulated results in terms of streamlines, heat lines and isotherms are displayed for various values of the model parameters, which govern the flow. Findings: The Nusselt number, friction factor and the thermal efficiency index are also determined for the pertinent parameters varying different ratios of the hybrid nanoparticles. The simulated results showed that thermal buoyancy significantly controls the heat transfer, friction factor and thermal efficiency index. The highest thermal efficiency is obtained for the lowest Rayleigh number. Practical implications: This theoretical study is significantly relevant to the applications of the hybrid nanofluids electronic devices cooled by fans, manufacturing process, renewable energies, nuclear reactors, electronic cooling, lubrication, refrigeration, combustion, medicine, thermal storage, etc. Originality/value: The results showed that nanoparticle loading intensified the rate of heat transfer and thermal efficiency index at the expense of the higher friction factor or higher pumping power. The results further show that the heat transmission in Al2O3–Cu/water hybrid nanofluid at a fixed value of intensified $\phi_{hnf}$ compared to the Al2O3/water nanofluid when an amount of higher conductivity nanoparticles (Cu) added to it. Besides, the rate of heat transfer in Cu/water nanofluid declines when the lower thermal conductivity Al2O3 nanoparticles are added to the mixture.

Original languageEnglish
Pages (from-to)196-218
Number of pages23
JournalInternational Journal of Numerical Methods for Heat and Fluid Flow
Issue number1
Publication statusPublished - Jan 3 2022
Externally publishedYes


  • Finite element method
  • Free convection
  • Hybrid nanofluid
  • Nanofluid
  • Rectotrapezoidal enclosure

ASJC Scopus subject areas

  • Mechanical Engineering
  • Aerospace Engineering
  • Engineering (miscellaneous)
  • Computational Mechanics


Dive into the research topics of 'Free convective heat transfer efficiency in Al2O3–Cu/water hybrid nanofluid inside a rectotrapezoidal enclosure'. Together they form a unique fingerprint.

Cite this