The effects of nanorod aspect ratio on Poiseuille flow and convective heat transfer of a nanofluid were studied numerically. A coupled model was proposed that considered the non-uniformity of the nanoparticle volume fraction and the orientation distribution. The thermal properties of the base fluid varied with temperature, and the nanofluid viscosity and thermal conductivity were correlated with the particle volume fraction based on experimental data. The model was verified useful to predict nanofluid flow that contains nanorods by comparing the numerical results with experimental data. The non-uniformity of nanorod volume fraction distribution increases near the boundary when the aspect ratio is larger. The nanorods orient nearly randomly-in-space along the flow center and align around the flow direction when particles migrate towards the wall. The flow resistance increases with the augment of the nanorod aspect ratio. The radial velocity profile of the fully developed Poiseuille flow is flattened due to the non-uniformity of the apparent stress, and the effect is enhanced with the increase of the nanorod aspect ratios. The convective heat transfer and overall thermal performance of the nanofluids is enhanced with the augment of the nanorod aspect ratio, especially in the low-flow-rate region. Hence, non-spherical nanofluids can be applied to cooling applications in minichannels with low-power consumption.

数值研究了纳米棒长径比对泊流流动和对流换热的影响。提出了考虑纳米颗粒体积分数和取向分布的不均匀性的耦合模型。基础流体的热性质随温度而变化，并且基于实验数据，纳米流体的粘度和热导率与颗粒体积分数相关。通过将数值结果与实验数据进行比较，证实该模型可用于预测包含纳米棒的纳米流体流动。当长径比较大时，纳米棒体积分数分布的不均匀性在边界附近增加。当粒子向壁迁移时，纳米棒几乎沿着流动中心在空间中定向，并在流动方向上对齐。流阻随着纳米棒长宽比的增加而增加。由于表观应力的不均匀性，完全展开的泊瓦型流动的径向速度分布曲线变得平坦，并且随着纳米棒长径比的增加，效果得到了增强。纳米流体的对流传热和整体热性能随着纳米棒纵横比的增加而增强，尤其是在低流量区域。因此，非球形纳米流体可以以低功耗应用于微型通道中的冷却应用。纳米流体的对流传热和整体热性能随着纳米棒纵横比的增加而增强，特别是在低流量区域。因此，非球形纳米流体可以以低功耗应用于微型通道中的冷却应用。纳米流体的对流传热和整体热性能随着纳米棒纵横比的增加而增强，特别是在低流量区域。因此，非球形纳米流体可以以低功耗应用于微型通道中的冷却应用。