La Porta A, Voth G A, Crawford A M, Alexander J, Bodenschatz E
Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853-2501, USA.
Nature. 2001 Feb 22;409(6823):1017-9. doi: 10.1038/35059027.
The motion of fluid particles as they are pushed along erratic trajectories by fluctuating pressure gradients is fundamental to transport and mixing in turbulence. It is essential in cloud formation and atmospheric transport, processes in stirred chemical reactors and combustion systems, and in the industrial production of nanoparticles. The concept of particle trajectories has been used successfully to describe mixing and transport in turbulence, but issues of fundamental importance remain unresolved. One such issue is the Heisenberg-Yaglom prediction of fluid particle accelerations, based on the 1941 scaling theory of Kolmogorov. Here we report acceleration measurements using a detector adapted from high-energy physics to track particles in a laboratory water flow at Reynolds numbers up to 63,000. We find that, within experimental errors, Kolmogorov scaling of the acceleration variance is attained at high Reynolds numbers. Our data indicate that the acceleration is an extremely intermittent variable--particles are observed with accelerations of up to 1,500 times the acceleration of gravity (equivalent to 40 times the root mean square acceleration). We find that the acceleration data reflect the anisotropy of the large-scale flow at all Reynolds numbers studied.
流体粒子在波动压力梯度作用下沿不规则轨迹被推动时的运动，是湍流中输运和混合的基础。这在云的形成和大气输运、搅拌化学反应器和燃烧系统中的过程以及纳米颗粒的工业生产中都至关重要。粒子轨迹的概念已成功用于描述湍流中的混合和输运，但一些至关重要的问题仍未得到解决。其中一个问题是基于1941年科尔莫戈罗夫尺度理论的流体粒子加速度的海森堡 - 亚格洛姆预测。在此，我们报告了使用一种改编自高能物理的探测器进行的加速度测量，该探测器用于在雷诺数高达63000的实验室水流中跟踪粒子。我们发现，在实验误差范围内，在高雷诺数下实现了加速度方差的科尔莫戈罗夫尺度。我们的数据表明，加速度是一个极其间歇性的变量——观察到粒子的加速度高达重力加速度的1500倍（相当于均方根加速度的40倍）。我们发现，加速度数据反映了在所研究的所有雷诺数下大尺度流动的各向异性。
