本文以兩相模型模擬奈米流體於均勻等壁溫三維扭曲橢圓管紊流強制對流之數值計算。應用控制體積法數值求解紊流強制對流奈米流體之橢圓、耦合、穩態之三維統御偏微分方程式。統御方程式則使用標準"k-ω" 紊流模型求解。研究參數包含雷諾數("10000 ≤ Re ≤ 15000" )、奈米粒子體積濃度("1 ≤ ϕ ≤ 4%" )，與節距長度("96mm ≤ d ≤ 192mm" )。首先以參考文獻中純水於扭曲橢圓管之實驗數據作驗證，其結果相當吻合，最大誤差在4%以內，再進一步延伸應用至奈米流體。
文中比較不同節距的扭曲橢圓管在等溫壁面時的對流熱傳與流場特性。模擬結果顯示與橢圓直管相比，流體流經扭曲橢圓管時產生旋轉，造成熱傳性能的增強。分析二次流與溫度分布，結果顯示扭曲橢圓管中因扭曲而產生的二次流造成奈米流體的混合。雖然可以提高傳熱能力，但扭曲橢圓管引起的擾動也會增加壓降。在研究範圍內，扭曲橢圓管之平均紐賽數與壓降，會隨著雷諾數與奈米粒子體積濃度增加而增加，並隨著節距長度增加而減少。
此外，以場協同原理解釋二次流對於熱傳的影響，並計算橢圓扭曲管中的耗散率。結果顯示在扭曲橢圓管中，扭曲的壁面使速度與溫度梯度有更好的協同性，因此可提高熱傳。而雷諾數與奈米粒子體積濃度增
加與節距長度縮短時，耗散量會增加，熱阻減少，傳熱效率較佳。
但若考慮摩擦阻抗的影響，雷諾數降低時會有較高的熱性能因子。

Numerical simulations by two-phase models of Al2O3/Water nanofluid forced convection in a three-dimensional twisted elliptical tube with uniform wall temperature are investigated using the finite volume approach. Flow resistance and heat transfer characteristics of nanofluids in the twisted elliptical tube are studied with the parameters including Reynolds number, nanoparticle volume concentration, and the twist pitch. Effects of the above-mentioned parameters on the performance of the twisted elliptical tubes are analyzed and the overall thermal-hydraulic performance is evaluated. In addition, the influence of the secondary flow on heat transfer is explained with the field synergy principle, and the entransy dissipation rate in the twist elliptical tube is calculated. The results show that in the twisted elliptical tubes, rotational motions are produced in the flowing nanofluid, enhancing the heat transfer performance compared with an oval tube. The average Nusselt number and the pressure drop both increase with increasing Reynolds number and nanoparticle volume concentration, while both decrease with the increasing of the twist pitch. Increase of Reynolds number and volume concentration of nanoparticles, and decrease of the pitch length yield more entransy dissipation and reduce thermal resistant, and the heat transfer process is more efficient. When the effect of pressure drop is considered, the thermal performance factor would be enhanced as Reynolds number decreases.

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