Line statistics: Stretching rate of passive lines in turbulence
Line statistics: Stretching rate of passive lines in turbulence
复制标题
线路统计：湍流中被动线路的拉伸率
DOI：
10.1063/1.1423286
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发表时间：
2002
影响因子：
4.6
通讯作者：
S. Goto
中科院分区：
文献类型：
--
作者：
S. Kida;S. Goto
对统计平稳各向同性不可压缩湍流中的无源线进行了数值跟踪。线长随时间呈指数增长，exp [γt]的拉伸率γ=0.17 （Kolmogorov时间）−1，比之前由许多被动矢量元素贡献的算术平均值估计的值大约30%。以往的研究低估是由于忽略了非均匀线拉伸引起的非均匀概率权值。如果考虑非均匀性的影响，则在演化的早期阶段直至几个柯尔莫哥洛夫时间内，真实拉伸率都能恢复。然而，此后，由于初始相邻向量元素的不断分离，它被高估了。
Passive lines in a statistically stationary isotropic incompressible turbulent flow are tracked numerically. The line length increases exponentially in time as exp [γt] with the stretching rate γ=0.17 (Kolmogorov time)−1 which is larger, by about 30%, than the value estimated before by the arithmetic mean of the contributions from many passive vector elements. The underestimation in previous studies is attributed to the negligence of nonuniform probability weight due to nonuniform line stretching. If the effects of nonuniformity are taken into account, the true stretching rate is recovered in the early stage of evolution up to several Kolmogorov times. Thereafter, however, it is overestimated owing to the continual separation of initially adjacent vector elements.