A phenomenological model for turbulent heat flux in high-speed flows with shock-induced flow separation
A phenomenological model for turbulent heat flux in high-speed flows with shock-induced flow separation
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DOI：
10.1115/1.4038760
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发表时间：
2018-05
影响因子：
2
通讯作者：
Utkarsh Pathak;Subhajit Roy;K. Sinha
中科院分区：
文献类型：
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作者：
Utkarsh Pathak;Subhajit Roy;K. Sinha
冲击波撞击湍流边界层的高速流动对当前的计算方法和模型提出了严峻的挑战。具体来说，使用传统湍流模型的雷诺平均纳维斯托克斯模拟严重高估了峰值壁热通量。这是因为普朗特数恒定假设在存在强烈的冲击波逆压梯度的情况下失效。实验数据表明，在逆压梯度作用下，边界层中的湍流普朗特数有所减少。我们使用现象学方法根据可用数据开发代数模型，并将其转换为可用于具有冲击引起的流动分离的高速流动的形式。冲击非稳态 k-ω 模型被用作基线，因为它可以很好地预测流动分离和逆压梯度区域。新模型显着改进了重新附着点附近的峰值热通量预测。该公式适用于附着流和分离流。此外，公式的简单性使其可以在现有 CFD 代码中轻松实现。
High-speed flows with shock waves impinging on turbulent boundary layers pose severe challenge to current computational methods and models. Specifically, the peak wall heat flux is grossly over-predicted by Reynolds-averaged Navier Stokes simulations using conventional turbulence models. This is because of the constant Prandtl number assumption, which fails in the presence of strong adverse pressure gradient of the shock waves. Experimental data suggest a reduction of the turbulent Prandtl number in boundary layers subjected to adverse pressure gradient. We use a phenomenological approach to develop an algebraic model based on the available data, and cast it in a form that can be used in high-speed flows with shock-induced flow separation. The shock-unsteadiness k-ω model is used as the baseline, since it gives good prediction of flow separation and the regions of adverse pressure gradient. The new model gives marked improvement in the peak heat flux prediction near the reattachment point. The formulation is applicable to both attached and separated flows. Additionally, the simplicity of the formulation makes it easily implementable in existing CFD codes.