Fast and slow changes of the length of gradient trajectories in homogeneous shear turbulence
Fast and slow changes of the length of gradient trajectories in homogeneous shear turbulence
复制标题
均匀剪切湍流中梯度轨迹长度的快速和缓慢变化
DOI：
10.1007/978-3-642-03085-7_136
复制
发表时间：
2009
影响因子：
8.6
通讯作者：
N. Peters
中科院分区：
文献类型：
--
作者：
P. Schäfer;M. Gampert;Lipo Wang;N. Peters
标量场中的梯度轨迹最近在耗散元素[1][2]的背景下受到关注，而耗散元素又对非预混燃烧中的小火焰概念感兴趣[3]。耗散元素是标量场中的空间填充区域，定义为使得从元素内的任何点开始的梯度轨迹在上升和下降方向上到达相同的最小值和最大值点。梯度轨迹优先通过扩散和广泛应变的联合作用已被平滑的标量场的区域。由于在这些区域中的广泛应变是积分时间尺度T的倒数的数量级，量纲分析预测耗散元件的平均长度lm是泰勒长度的数量级[4]。
Gradient trajectories in scalar fields have recently received attention in the context of dissipation elements [1], [2] which in turn are of interest for the flamelet concept in nonpremixed combustion [3]. Dissipation elements are space filling regions in a scalar field defined such that gradient trajectories starting from any point within the element in ascending and descending directions reach the same minimum and maximum points. Gradient trajectories advance preferentially through regions of the scalar field that have been smoothed by the combined action of diffusion and extensive strain. Since the extensive strain in these regions is of the order of the inverse of the integral time scale T, dimensional analysis predicts the mean length l m of dissipation elements to be of the order of the Taylor length [4].