本文利用FLOW-3D套裝軟體的三維數值模式，以求解雷諾平均方程式 (RANS) 並結合標準 k-ϵ 閉合紊流模式進行模擬，再利用體積分率法 (FAVOR) 模擬長管 (long pipe) 形射流管，以求得射流管之速度分布為紊流完全發展流分布；進行紊流射流於規則波環境下之探討。
本研究首先進行兩組模式驗證模擬，分別為自由射流 (free jet) 的驗證；以及自由射流於規則波環境下之試驗驗證。前者與諸多自由射流實驗量測得到之數據相比亦吻合良好；其中包括中間軸速度的衰減率、自由射流之自我相似性、周邊水體對射流之捲增以及紊流動能；後者則與 Hsiao 等人 (2011) 之實驗做比較。
此外，本研究利用 FLOW-3D 三維數值模式之特性，進一步討論自由射流於規則波環境下核心區域 (potential core) 以及近域流場 (near field) 之斷面速度分布狀況；其結果亦模擬出 Chang (2009) 觀察到的斷面水平速度分布；本研究發現射流的斷面水平速度分布與規則波之相位存在密切的關係、並深入探討不同相位下斷面之速度分布以及不同波高與不同週期之影響。

A three-dimensional numerical investigation of a turbulent round jet discharged into a regular wave field is presented. The FLOW-3D modeling based on the Reynolds Averaged Navier-Stokes (RANS) equations combined with k-ϵ turbulence closure model was adopted. In addition, the Fractional Area/Volume Obstacle Representation method (FAVOR) is used to simulate a long pipe type round jet nozzle.
To validate the present numerical model, the comparisons between simulated results and available experimental data in literatures are necessary. We first test a jet discharged into a stagnant environment, which contains velocity decay on jet centerline, self-similarity of the mean flow, mass entrainment into the jet and turbulence intensity. Then, numerical experiments are carried out to compare with results by Hsiao et al. (2011) for a turbulent round jet discharged into regular wave field. Generally, the present numerical results show high degree of accuracy, compared to the existing experiments.
Based on the three-dimensional model FLOW-3D, we also examine the cross-sectional velocity profiles in both potential core region and near field region. The present numerical results show similar velocity profiles with Chang et al. (2009). The results also showed that the cross-sectional velocity profiles are significantly affected by different wave phases. Furthermore, additional numerical experiments were carried out to examine how the wave nonlinearity and periods affect the jet hydrodynamics.

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