标题： 充分发展湍流中的流体粒子加速度 显示英文标题

标题： Fluid Particle Accelerations in Fully Developed Turbulence

摘要： 流体粒子在波动压力梯度的作用下沿不规则轨迹运动，这是湍流中传输和混合的基本现象。 这在云的形成和大气传输中至关重要，也存在于搅拌化学反应器和燃烧系统中的过程，以及纳米颗粒工业生产过程中。 粒子轨迹的观点已被成功用于描述湍流中的混合和传输，但一些基本问题仍未解决。 其中一个问题是基于Kolmogorov（K41）1941年尺度理论的海森堡-亚格隆关于流体粒子加速度的预测。 在这里，我们报告了使用从高能物理中适应而来的探测器，在雷诺数高达63,000的实验室水流中追踪粒子的加速度测量结果。 我们发现，在高雷诺数下实现了加速度方差的普遍K41尺度。 我们的数据表明存在强烈的间歇性——观察到的加速度可达重力加速度的1500倍（40倍均方根值）。 最后，我们发现加速度在所有研究的雷诺数下都表现出大尺度流动的各向异性。 显示英文摘要

摘要： 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 perspective 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 (K41). 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 universal K41 scaling of the acceleration variance is attained at high Reynolds numbers. Our data show strong intermittency---particles are observed with accelerations of up to 1,500 times the acceleration of gravity (40 times the root mean square value). Finally, we find that accelerations manifest the anisotropy of the large scale flow at all Reynolds numbers studied.