Abstract In this paper, numerical simulation is performed to investigate the turbulent thermal convection flow and heat transfer characteristics of nanofluids inside a cubical enclosure with partially mounted heat and cold source. A transient, three-dimensional, two-phase mixture model with LamBremhorst k − ϵ turbulence model is developed, validated and solved using finite difference method. The heat transfer performance of different water based nanofluids such as aluminum oxide (Al2O3), copper (Cu) and silver (Ag) are investigated for a wide range of Grashof numbers (Gr) varying between 106 ≤ Gr ≤ 1010. The nanoparticle diameter (dp) and volume fractions (ϕ) are varied between 20nm ≤ dp ≤ 80nm and 2% ≤ ϕ ≤ 4%. The results indicate that the random Brownian motion of nanoparticles increases the thermal convection and enhances the rate of energy exchange between the fluid and particle phase. The average heat transfer rate increases with increase in Grashof number and volume fraction. It is found that the effect of volume fraction on average heat transfer rate is more effective in transitional flows than fully turbulent flows. The average heat transfer rate increases with decrease in particle size and the influence of nanoparticle size on heat transfer enhancement are significant in turbulent flows than transitional flows.

中文翻译：

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使用两相混合模型的立方体外壳中纳米流体的湍流热对流

摘要 本文通过数值模拟研究了局部安装热源和冷源的立方体外壳内纳米流体的湍流热对流和传热特性。使用有限差分方法开发、验证和求解具有 LamBremhorst k − ϵ 湍流模型的瞬态三维两相混合模型。研究了不同水基纳米流体如氧化铝 (Al2O3)、铜 (Cu) 和银 (Ag) 的传热性能，其格拉肖夫数 (Gr) 在 106 ≤ Gr ≤ 1010 之间变化。 dp) 和体积分数 (ϕ) 在 20nm ≤ dp ≤ 80nm 和 2% ≤ ϕ ≤ 4% 之间变化。结果表明，纳米颗粒的随机布朗运动增加了热对流并提高了流体和颗粒相之间的能量交换速率。平均传热率随着 Grashof 数和体积分数的增加而增加。发现体积分数对平均传热率的影响在过渡流中比完全湍流更有效。平均传热速率随着粒径的减小而增加，纳米粒径对传热增强的影响在湍流中比过渡流中显着。发现体积分数对平均传热率的影响在过渡流中比完全湍流更有效。平均传热速率随着粒径的减小而增加，纳米粒径对传热增强的影响在湍流中比过渡流中显着。发现体积分数对平均传热率的影响在过渡流中比完全湍流更有效。平均传热速率随着粒径的减小而增加，纳米粒径对传热增强的影响在湍流中比过渡流中更显着。