This work computationally explores the two-phase flow of nanofluids and their thermal energy transport coefficients in 3D diamond-shaped cavities with square-shaped barriers having reducing dimensions. Materials with two emissivity values, $ϵ=0.3$ and 0.9, have been considered to investigate the effect of the radiation thermal energy transport coefficient while the hot side is maintained at 400 or 500 K. Two values of the Rayleigh number, Ra = 10⁶ and 10⁸, are used for the study. Cu nanoparticles (NPs) with an average size of 25 nm have been used at a concentration of 0.01–0.05% in the base fluid. The temperature gradients and thermal energy transport coefficient characteristics are enhanced by raising the volume concentration of nanoparticles, but the streamlines do not alter substantially. By increasing Ra, the thermal energy transport coefficient rate is further augmented. It is also found that increasing the Ra and volume concentration of NPs results in enhanced heat transfer inside a cavity, while a change in the emissivity coefficient has no significant impact on the thermal and flow characteristics of the nanofluid. For each case, there is an optimum NP volume fraction for each model that leads to the highest Nusselt number.

这项工作通过计算探索了纳米流体的两相流及其在具有减小尺寸的方形屏障的 3D 菱形腔中的热能传输系数。具有两个发射率值的材料，$\epsilon =0.3$和 0.9，已被考虑用于研究热侧保持在 400 或 500 K 时辐射热能传输系数的影响。瑞利数的两个值，Ra = 10 ⁶和 10 ⁸, 用于研究。平均尺寸为 25 nm 的铜纳米粒子 (NPs) 在基液中的使用浓度为 0.01-0.05%。温度梯度和热能传输系数特性通过提高纳米粒子的体积浓度而增强，但流线没有实质性改变。通过增加Ra，热能传输系数率进一步增加。还发现增加纳米颗粒的 Ra 和体积浓度会导致腔内传热增强，而发射系数的变化对纳米流体的热和流动特性没有显着影响。对于每种情况，每个模型都有一个最佳的 NP 体积分数，可以导致最高的 Nusselt 数。