本文主要以數值模擬三維鰭片散熱器之不可壓縮紊流流場與熱傳特性，且工作流體為空氣。文中比較了兩種不同形狀的鰭片散熱器，包括圓形和方形，並討論了兩種鰭片散熱器在對齊式排列與交錯式排列之散熱性能。紊流統御方程式則是以有限體積法為基礎，配合三種根據雷諾平均Naviers-Stokes 近似的 紊流模型來求解本問題。在本文的研究範圍內，可實現化 紊流模型相對於另外兩個紊流模型在整體性能上表現較好。
往後的數值計算都將使用可實現化 紊流模型，其研究參數包含：鰭片高度H、鰭片直徑D和雷諾數Re，其研究探討的範圍為7mm<H<10mm、0.75mm<D<2mm及2000<Re<12600。將模擬結果與文獻上的實驗數據作驗證，其結果相吻合。圓形鰭片散熱器因為形狀相對於方形鰭片散熱器較為流線，所以在壓降方面較方形鰭片散熱器小，但是熱傳效益較不如方形鰭片散熱器。文中也發現交錯式排列對流場的擾動性較佳，故熱傳性能優於對齊式排列的鰭片散熱器。不管是交錯式或對齊式鰭片在熱阻、壓降和熵增都有相同的趨勢。
此外，在經過與實驗值的驗證後，文中利用基因演算法來對鰭片散熱器作最佳化，並以熵增為目標函數，計算其最小值，熵增可由壓降與熱阻計算而得。對於對齊式與交錯式鰭片散熱器，分別對其最佳化，且相對的性能分析將在文中討論。

Three-dimensional incompressible turbulent fluid flow and heat transfer of pin fin heat sinks using air as a cooling fluid are numerically studied in this study. Two different kinds of pin fins are compared in the thermal performance, including circular and square cross sections, both are in-line and staggered arrangements. The turbulent governing equations are solved using a control-volume-based finite-difference method by employing three well-known turbulence models based on Reynolds-averaged Navier-Stokes (RANS) approach. Overall performance of realizable turbulence model is much better in comparing with other turbulence models in the studied ranges.
Subsequently, numerical computations are performed with the realizable turbulence for the parameters studied, the fin height H, fin diameter D, and Reynolds number (Re) in the range of 7mm<H<10mm, 0.75mm<D<2mm, 2000<Re<12600, respectively. The numerical results are validated with available experimental data in the literature and good agreement has been found. It indicates that circular pin fins is streamlined in comparing with the square pin fins, the pressure drop is small than that of square pin fins, and heat transfer is not as good as the square pin fins. The thermal performance of the staggered pin fins is better than that of in-line pin fins because the staggered arrangements produce large disturbance. Both in-line and staggered arrangements show the same behavior for thermal resistance, pressure drop, and the entropy generation.
In addition, after the validation of the numerical results, genetic algorithm (GA) is applied for the optimization of pin-fin heat sinks. Entropy generation due to heat transfer and pressure drop across pin-fins is minimized by using GA. Both in-line and staggered arrangement are studied and their relative performance is compared.

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