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–Al2${}_2$${}_2$O3${}_3$${}_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–Al2${}_2$${}_2$O3${}_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.

自然对流的被动特征鼓励对该领域的持续研究。这项研究工作研究了波状垂直表面空腔内的自然对流，包括立在空腔底部的热源块。使用的液体是水-铜-铝混合液2${}_2$${}_2$氧3${}_3$${}_3$纳米流体。垂直波浪面在低温下固定，而热源在较高温度下保持恒定。应用伽辽金有限元方法获得数值解。除了常见的可视化工具外，本文还使用了热线工具。从结果发现，努塞尔数与热源长度成正比。此外，杂化水-Cu-Al2${}_2$${}_2$氧3${}_3$纳米流体表现出比纯水和其他常规纳米流体更高的努塞尔数。混合纳米流体在以下温度下获得的平均传热百分比$\phi =0.02$分别比纯水和其他纳米流体高13.7%和5%。