Ayyalasomayajula S, Gylfason A, Collins L R, Bodenschatz E, Warhaft Z
Mechanical & Aerospace Engineering, Cornell University, Ithaca, New York, USA.
Phys Rev Lett. 2006 Oct 6;97(14):144507. doi: 10.1103/PhysRevLett.97.144507. Epub 2006 Oct 5.
We describe Lagrangian measurements of water droplets in grid generated wind tunnel turbulence at a Taylor Reynolds number of R(lambda)=250 and an average Stokes number (St) of approximately 0.1. The inertial particles are tracked by a high speed camera moving along the side of the tunnel at the mean flow speed. The standardized acceleration probability density functions of the particles have spread exponential tails that are narrower than those of a fluid particles (St approximately 0) and there is a decrease in the acceleration variance with increasing Stokes number. A simple vortex model shows that the inertial particles selectively sample the fluid field and are less likely to experience regions of the fluid undergoing the largest accelerations. Recent direct numerical simulations compare favorably with these first measurements of Lagrangian statistics of inertial particles in highly turbulent flows.
我们描述了在泰勒雷诺数(R(\lambda)=250)和平均斯托克斯数（(St)）约为(0.1)的网格生成风洞湍流中对水滴的拉格朗日测量。惯性粒子由沿着风洞侧面以平均流速移动的高速摄像机跟踪。粒子的标准化加速度概率密度函数具有比流体粒子（(St)约为(0)）更窄的扩展指数尾部，并且随着斯托克斯数的增加，加速度方差减小。一个简单的涡旋模型表明，惯性粒子有选择地采样流场，并且不太可能经历流体中加速度最大的区域。最近的直接数值模拟与这些在高湍流流动中对惯性粒子拉格朗日统计的首次测量结果吻合良好。
