Impacts of amplitude and heat source on natural convection of hybrid nanofluids into a wavy enclosure via heatline approach

Abstract

The passive feature of natural convection encourages continuous investigation on this field. This research work studies the natural convection inside a cavity of wavy vertical surfaces, including a heat source block standing on the base of cavity. The employed liquid is a hybrid water–Cu–Al${}_2$O${}_3$ nanofluid. The vertical wavy surfaces are fixed at low temperature, while the heat source remains constant at a higher temperature. The Galerkin finite element method is applied to obtain the numerical solutions. Besides the common visualization tools, the heatlines tool is used in this paper as well. It is found from the outcomes that the Nusselt number is purely proportional to the length of the heat source. In addition, the hybrid water–Cu–Al${}_2$O${}_3$ nanofluid exhibits a higher Nusselt number than that corresponding to a pure water and as well as other regular nanofluids. The percentages of the average heat transfer gained by the hybrid nanofluid at $\varphi =0.02$ are 13.7% and 5% higher than those for pure water and other nanofluids.

Keywords:

• Complex wavy cavity
• heatline approach
• natural convection
• hybrid nanofluid
• heat source

Acknowledgments

We are grateful for the financial support received from the Malaysian Ministry of Education under the research grant FRGS/1/2019/STG06/UKM/01/2. We thank the respected reviewers for their constructive comments which clearly enhanced the quality of the manuscript.

Disclosure statement

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