A study of Cu/Ag nanoparticle shape-augmented heat transfer in Darcy–Brinkman–Forchheimer flow in a square cavity

ABSTRACT

The present work is an analysis of heat transfer flow phenomena due to the natural convection process in a square enclosure filled with a porous medium containing Cu/Ag water-based nanofluid. Multiphysics faceted Darcy–Brinkman–Forchheimer model is used to govern the flow in a porous medium. Different shapes (sphere, blades, bricks, cylinders, and platelets) of the nanoparticles are considered to examine their influence on heat transfer. The model has been solved by the finite element method. The numerical results have been validated against results from the literature. Computed results have been presented graphically by streamlines, isotherms, local and cumulative Nusselt number plots for various physical parameters, Rayleigh number (Ra), inverse Darcy number ($D{a}^{-1}$), Brinkman effect (Λ), the porosity of the porous medium$\left(ϵ\right)$ and solid volume fraction of the nanoparticles$\left(\varphi \right)$. The study pioneers the investigation on the significance of the combined influence of effective viscosity and nanofluid viscosity through the Brinkman effect and reports its importance on nanoparticle shape-based heat transfer augmentation. Cost-effective Cu nanoparticles are shown to augment the heat transfer as achieved by the conventionally preferred Ag nanoparticles. While spherical nanoparticles outperform other shapes in heat transfer augmentation for Brinkman effect $<1$, the blade-shaped nanoparticles dominate when Brinkman effect $\ge 1$. Higher heat transfer rates are noticed for lesser values of the Brinkman effect, high porosity, the maximum volume fraction of the nanoparticles, high Rayleigh number, and low permeability with spherical-shaped nanoparticles than blade-shaped nanoparticles.

KEYWORDS:

• Nanofluid
• Darcy–Brinkmann–Forchheimer
• finite element method

Acknowledgments

One of the authors B. Mallikarjuna, acknowledges the fund by TEQIP III, IIT Kanpur and TEQIP III, BMS College of Engineering, Bangalore.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

One of the authors B. Mallikarjuna, acknowledges the fund by TEQIP III, IIT Kanpur and TEQIP III, BMS College of Engineering, Bangalore.