Stochastic analysis of the impact of freestream conditions on the aerodynamics of a rectangular 5:1 cylinder
Stochastic analysis of the impact of freestream conditions on the aerodynamics of a rectangular 5:1 cylinder
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DOI：
10.1016/j.compfluid.2016.06.008
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发表时间：
2016-09
影响因子：
2.8
通讯作者：
A. Mariotti;M. Salvetti;P. S. Omrani;J. Witteveen
中科院分区：
文献类型：
--
作者：
A. Mariotti;M. Salvetti;P. S. Omrani;J. Witteveen
在弦深比为5的矩形圆柱体气动性能基准中，不确定性起着重要的作用。特别是，除了建模和数值误差外，在数值模拟中，由于设置参数的不确定性，很难准确地再现实验条件，这些参数有时无法精确控制或表征。本文采用概率方法和二维URANS数值模拟方法，研究了BARC构型入流条件不确定性的影响。研究了以下不确定的设置参数：入射角、自由流纵向湍流强度和自由流湍流长度尺度。采用随机配置法实现了不确定性在三个设定参数中的概率传播。这导致了基于Level-2 Clenshaw-Curtis积分点的Smolyak稀疏网格扩展的25个URANS模拟。通过对不同网格大小重复相同的分析来估计离散化误差。同样，通过对雷诺应力和SSTk−ω模型进行不确定性量化，评价了湍流模拟的效果。最后，对设定参数的不同假设概率密度函数得到的结果进行了比较。所考虑的不确定性的传播并不能单独解释BARC实验数据的分散。对于某些感兴趣的量，湍流模拟的效果比流入条件中的不确定性的影响更重要。对所考虑的不确定性的敏感性也随着湍流模型的不同而不同，用雷诺应力模型得到的结果的变异性较大。在所有情况下，来流湍流长度尺度都是最不重要的参数。
Uncertainty plays a significant role in the Benchmark on the Aerodynamics of a Rectangular Cylinder (BARC) with a chord-to-depth ratio of 5. In particular, besides modeling and numerical errors, in numerical simulations it is difficult to exactly reproduce the experimental conditions due to uncertainties in the set-up parameters, which sometimes cannot be exactly controlled or characterized. In this study, the impact of the uncertainties in the inflow conditions of the BARC configuration is investigated by using probabilistic methods and two-dimensional URANS simulations. The following uncertain set-up parameters are investigated: the angle of incidence, the freestream longitudinal turbulence intensity and the freestream turbulence length scale. The stochastic collocation method is employed to perform the probabilistic propagation of the uncertainty in the three set-up parameters. This results in 25 URANS simulations based on the Smolyak sparse grid extension of the level-2 Clenshaw-Curtis quadrature points. The discretization error is estimated by repeating the same analysis on different grid sizes. Similarly, the effect of turbulence modeling is appraised by carrying out the uncertainty quantification for the Reynolds stress and the SST k− ω models. Finally, the results obtained for different assumed probability density functions of the set-up parameters are compared. The propagation of the considered uncertainties does not explain alone the dispersion of the BARC experimental data. For certain quantities of interest, the effect of turbulence modeling is more important than the impact of the uncertainties in inflow conditions. The sensitivity to the considered uncertainties also varies with the turbulence model, with a larger variability of the results obtained with the Reynolds stress model. The inflow turbulence length scale is in all cases the least important parameter.