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On the uncertainty of boundary-layer parameters from Ensemble PTV data
Measurement Science and Technology ( IF 2.4 ) Pub Date : 2021-05-28 , DOI: 10.1088/1361-6501/abfad0
R Castellanos , C Sanmiguel Vila , A Güemes , S Discetti

The recent advancements in high-resolution turbulence-statistics computation from ensemble particle tracking velocimetry (EPTV) data are now opening new possibilities in turbulent-flow characterisation. Measurements of full-field boundary layer profiles with a fine resolution close to the wall and up to the freestream with one single imaging setup are now feasible, thus paving the way to direct characterisation of turbulent-boundary-layer (TBL) parameters with composite-profile formulations. In this work, we build a framework for the estimation of the uncertainty of EPTV in performing this task. The effect of systematic errors due to finite spatial resolution and of random error due to convergence are investigated under different window size. Then we introduce random errors to simulate the effects on convergence issues on the velocity profile and, consequently, on the estimation of turbulent-boundary-layer parameters. The statistical dispersion of the estimated parameters provides an estimation of the uncertainty range. We validate with experimental data this flexible tool to estimate a priori the expected uncertainty level of the most relevant turbulent-boundary-layer parameters in zero-pressure-gradient TBL, being the method based on existing profiles from high-fidelity simulation or from analytical composite-profile formulations when such data are not available.



中文翻译:

关于 Ensemble PTV 数据边界层参数的不确定性

来自集合粒子跟踪测速 (EPTV) 数据的高分辨率湍流统计计算的最新进展现在为湍流表征开辟了新的可能性。用一个单一的成像装置测量接近壁面和自由流的全场边界层轮廓现在是可行的,从而为使用复合材料直接表征湍流边界层 (TBL) 参数铺平了道路。轮廓配方。在这项工作中,我们建立了一个框架,用于估计 EPTV 在执行此任务时的不确定性。研究了不同窗口大小下有限空间分辨率引起的系统误差和收敛引起的随机误差的影响。然后我们引入随机误差来模拟收敛问题对速度剖面的影响,并且,因此,关于湍流边界层参数的估计。估计参数的统计分散提供了对不确定性范围的估计。我们用实验数据验证了这个灵活的工具来估计先验的是零压力梯度 TBL 中最相关湍流边界层参数的预期不确定性水平,该方法基于来自高保真模拟或分析复合剖面公式的现有剖面,当此类数据不可用时。

更新日期:2021-05-28
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