The free convection in a porous U-shaped shield containing Al₂O₃/H₂O nanofluid (NF) was examined using the two-phase (tp) mixture method. The results showed that the heat transfer (HT) rate and average Nusselt number (Nu_avg) were amended by increasing the volume fraction ($\phi$) of Al₂O₃ nanoparticles (NPs). An enhancement in Rayleigh number (Ra number) led to the turbulence of the NF flow; therefore, the Nu_avg enhanced. Moreover, adding Al₂O₃ NPs to the base fluid (water) enhanced the fluid conductivity, resulting in the increase of Nu_avg In this study, the results of the tp method were compared with the single-phase (sp) metrhod. It was concluded that the single-phase method is described the effects of the NPs appropriately, but it could not correctly represent the performance of NP. The buoyancy force was weak at a low Ra numbers (such as Ra = 1000). Therefore, the arrangement of isotherms is remained unchanged. However, in large quantities such as Ra = 100000, the buoyancy force is increased; so, the uniform order and arrangement of the isotherms are disturbed.

使用两相 (tp) 混合法检测了含有 Al ₂ O ₃ /H ₂ O 纳米流体 (NF)的多孔 U 形屏蔽层中的自由对流。结果表明，通过增加体积_分数（$\phi$) 的 Al ₂ O ₃纳米粒子 (NPs)。瑞利数（Ra 数）的增强导致 NF 流的湍流；因此，Nu _avg增强了。此外，在基础流体（水）中添加 Al ₂ O ₃ NPs 增强了流体电导率，导致 Nu _avg增加在本研究中，将 tp 方法的结果与单相 (sp) 方法的结果进行了比较。得出的结论是，单相方法恰当地描述了 NPs 的影响，但它不能正确地表示 NPs 的性能。在低 Ra 数（例如 Ra = 1000）时，浮力较弱。因此，等温线的排列保持不变。但是在Ra=100000等大的量下，浮力增大；因此，等温线的均匀顺序和排列被打乱。