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A methodology for the uncertainty quantification and sensitivity analysis of turbulence model coefficients.

机译:湍流模型系数不确定性量化和敏感性分析的方法。

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摘要

This thesis is concerned with the propagation of uncertainties in the values of turbulence model coefficients and parameters. These empirical coefficients and parameters are determined from experiments or direct numerical simulation results performed on turbulent flows and are subject to uncertainty. In this work, the widely used k -- epsilon turbulence model is considered. It consists of model transport equations for the turbulence kinetic energy and the rate of turbulent dissipation. Both equations involve various model coefficients about which adequate knowledge is assumed in the form of probability density functions. The study, presented here, is carried out for a flow over a 2D backward-facing step configuration. The Latin Hypercube Sampling method is employed for the uncertainty quantification purposes as it requires a smaller number of samples compared to the conventional Monte-Carlo method. The mean values are reported for the flow output parameters of interest along with their associated uncertainties in the form of box plots. The results of the uncertainty quantification show that model coefficient variability has significant effects on the streamwise mean velocity in the recirculation region near the reattachment point and turbulence intensity along the free shear layer. The reattachment point location, pressure, and wall shear are also significantly influenced by the uncertainties of the coefficients. A sensitivity analysis has been performed to compliment the uncertainty quantification and is used to determine correlations between the coefficients and the outputs of interest. Partial Rank Correlation Coefficients are implemented as the sensitivity analysis method. The results of the sensitivity analysis show the smoothness parameter B to be the most critical.
机译:本文涉及湍流模型系数和参数值的不确定性的传播。这些经验系数和参数是根据对湍流进行的实验或直接数值模拟结果确定的,并且存在不确定性。在这项工作中,考虑了广泛使用的k-ε湍流模型。它由湍流动能和湍流耗散率的模型输运方程组成。这两个方程都涉及各种模型系数,以概率密度函数的形式假设有足够的知识。本文介绍的研究是针对2D向后步骤配置中的流程进行的。拉丁超立方采样方法用于不确定性量化,因为与传统的蒙特卡洛方法相比,它需要的样本数量更少。以箱形图的形式报告目标流量输出参数的平均值及其相关的不确定性。不确定性量化的结果表明,模型系数的可变性对靠近再附着点的再循环区域的水流平均速度和沿自由剪切层的湍流强度具有显着影响。重新连接点的位置,压力和墙剪也受到系数不确定性的显着影响。进行了灵敏度分析以补充不确定性量化,并用于确定系数和目标输出之间的相关性。偏秩相关系数被用作灵敏度分析方法。灵敏度分析的结果表明,平滑度参数B是最关键的。

著录项

  • 作者

    Dunn, Matthew C.;

  • 作者单位

    The University of Alabama in Huntsville.;

  • 授予单位 The University of Alabama in Huntsville.;
  • 学科 Engineering Aerospace.;Engineering Mechanical.
  • 学位 M.S.E.
  • 年度 2011
  • 页码 75 p.
  • 总页数 75
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 TS97-4;
  • 关键词

  • 入库时间 2022-08-17 11:44:37

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