论文标题

湍流边界层中的速度衍生物。第二部分:统计特性

Velocity Derivatives in Turbulent Boundary Layers. Part II: Statistical Properties

论文作者

George, William K., Stanislas, Michel, Foucaut, Jean-Marc, Laval, Jean-Philippe, Cuvier, Christophe

论文摘要

使用LMFL边界层功能中的双平面-PIV进行了实验,以确定估计湍流动能的平均耗散率($ \ varepsilon $)所需的所有衍生力矩,其Reynolds及其Reynolds强调了耗散张量,$ \ VAREPSILON_ _J} $ {ij} $。对于此实验,雷诺数为$re_θ= 7500 $或$re_τ= 2300 $。简而言之,该贡献的第一部分\ cite {stanislas20}详细讨论了耗散曲线以及计算其所需的所有十二个衍生矩。将数据与大致相同的雷诺数和先前结果的通道流DNS进行比较。它们还被用来评估重叠区域的最新理论结果。 在本第二部分中,实验和DNS结果用于评估“局部各向同性”,“局部轴对称”和“局部同质性”的假设。它们被扩展到包括完整的耗散张量,$ \ varepsilon_ {ij} $和``pseudo-Dissipation Tensor'',$ \ Mathcal {d} _ {ij} $并解释了散散量张量的强激态的强度。本研究的两个重要结果是,{\ it locarpropy}在重叠区域的外部极限内永远不是有效的,$ y/δ__{99} \ oft of 0.1 $;并且{\ it local轴对称}和{\ it local同质性}的假设在$ y^+ = 100 $的内部失败。引入了{\ it同质性在平行于墙壁的平面}的含义,以部分解释整个墙壁层的观察值。这个非常近的墙区域中的耗散特性表明,$ \ varepsilon_ {ij} $接近但与$ \ Mathcal {d} _ {ij} $不同。

An experiment was performed using Dual-plane-SPIV in the LMFL boundary layer facility to determine all of the derivative moments needed to estimate the average dissipation rate of the turbulent kinetic energy, $\varepsilon$, and its Reynolds stress counterpart the dissipation tensor, $\varepsilon_{ij}$. For this experiment, the Reynolds number was $Re_θ= 7500$ or $Re_τ= 2300$. Part I of this contribution \cite{stanislas20} presented in short the experiment and discussed in detail the dissipation profile and all twelve derivative moments required to compute it. The data were compared to a channel flow DNS at approximately the same Reynolds number and to previous results. They were also used to evaluate recent theoretical results for the overlap region. In this Part II the experimental and DNS results are used to evaluate the assumptions of `local isotropy', `local axisymmetry', and `local homogeneity'. They are extended to include the full dissipation tensor, $\varepsilon_{ij}$ and the `pseudo-dissipation tensor', $\mathcal{D}_{ij}$ and explain the strong anisotropy of the dissipation tensors observed. Two important results of the present study are that {\it local isotropy} is never valid inside the outer limit of the overlap region, $y/δ_{99} \approx 0.1$; and that the assumptions of {\it local axisymmetry} and {\it local homogeneity} fail inside of $y^+ =100$. The implications of {\it homogeneity in planes parallel to the wall} is introduced to partially explain observations throughout the wall layer. The dissipation characteristics in this very near wall region show that $\varepsilon_{ij}$ is close to but different from $\mathcal{D}_{ij}$ .

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