Decomposition of the turbulent kinetic energy field into regions of compressive and extensive strain
Decomposition of the turbulent kinetic energy field into regions of compressive and extensive strain
复制标题
将湍流动能场分解为压缩应变区域和扩展应变区域
DOI：
10.1088/0031-8949/2013/t155/014002
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发表时间：
2013
期刊：
影响因子：
2.9
通讯作者：
N. Peters
中科院分区：
文献类型：
--
作者：
M. Gampert;P. Schaefer;J. Goebbert;N. Peters
基于对均匀剪切湍流、均匀各向同性衰减湍流和槽道湍流的直接数值模拟，得到了沿梯度轨迹的两点速度差沿着梯度轨迹的标度Δun| s和瞬时湍动能场k极值点之间的关系。在第一步中，我们检查线性的Δun| s表示沿梯度轨迹沿着的分离弧长，a∞表示大耗散单元条件平均应变率的渐近值。然后，我们研究了标量极值点之间速度差的标度Δun|以及它们之间欧几里德距离P（l）的概率密度函数，条件是压缩和广泛的应变区域。我们观察到，虽然整体速度差沿着梯度轨迹和扩散连接的标量极值点之间表现出线性标度行为|l l，广泛的非线性方程组的条件速度差|l+ m和压缩区域m Δun|与K41理论相比，l− ε与l2/3成比例。整体的标度指数来自纯广延（压缩）的Δun的一部分|l+ Δun|而第二个贡献是由于不同区域的加权差异，因此涉及条件pdf P（l+）和P（l-）。我们发现，后者的关系尺度与l1/3。n的分解|l =两个贡献，分别与l2/3和l1/3缩放，因此产生了另一种解释所观察到的线性制度。
Based on direct numerical simulations of homogeneous shear turbulence, homogeneous isotropic decaying turbulence and a turbulent channel flow, the scaling of the two-point velocity difference along gradient trajectories 〈Δun|s〉 as well as between the extreme points of the instantaneous turbulent kinetic energy field k is studied. In the first step, we examine the linear 〈Δun|s〉∝s·a∞ scaling, where s denotes the separation arclength along a gradient trajectory and a∞ is the asymptotic value of the conditional mean strain rate of large dissipation elements. Then, we investigate the scaling of the velocity difference between scalar extreme points 〈Δun|l〉 as well as the probability density function of the Euclidean distance P(l) between them, conditioned on compressive and extensive strain regions. We observe that while the overall velocity difference along gradient trajectories and between diffusively connected scalar extreme points exhibits linear scaling behaviour 〈Δun|l〉∝l, the conditional velocity differences of extensive 〈Δun|l+〉 and compressive regions 〈Δun|l−〉 are in contrast to the K41 theory proportional to l2/3. The scaling exponent of the overall comes to one part from the purely extensive (compressive) 〈Δun|l+〉 (〈Δun|l−〉), while the second contribution is due to the difference in weighting the different regions, thus involving the conditioned pdfs P(l+) and P(l−). We find that the latter relation scales with l1/3. The decomposition of 〈Δun|l〉 into two contributions scaling with l2/3 and l1/3, respectively, hence yields an alternative explanation for the observed linear regime.
初始条件未知的均匀各向同性衰减湍流的渐近分析
影响因子：
1.9
作者：
Schaefer;Gampert;Goebbert;Gauding;Peters
通讯作者：
Peters
影响因子：
2.9
作者：
P. Schaefer;M. Gampert;N. Peters
通讯作者：
N. Peters
均匀各向同性衰减湍流中流线段的长度分布
影响因子：
4.6
作者：
P. Schaefer;M. Gampert;N. Peters
通讯作者：
N. Peters