The slip velocity of nearly neutrally buoyant tracers for large-scale PIV
The slip velocity of nearly neutrally buoyant tracers for large-scale PIV
复制标题
大型 PIV 的近中性浮力示踪剂的滑移速度
作者：
D. E. Faleiros;M. Tuinstra;A. Sciacchitano;F. Scarano
近中性浮力示踪剂的行为进行了研究，通过实验与充满氦气的肥皂泡和数值模拟。目前用于估计的重微粒和中性浮力颗粒的滑移速度的模型进行了审查和扩展，包括非定常力和颗粒雷诺数的影响。粒子运动分析通过数值模拟的直线振荡流，并在周围的翼型件内的粒子流参数空间，这是典型的大型PIV实验的流动。根据颗粒与流体的密度比、颗粒雷诺数和局部流动波动的频率，获得了估计颗粒滑移速度的经验关系。开发的模型被应用于评估的滑移速度的氦气填充的肥皂泡在大规模的实验中进行的德国-荷兰风（DNW）隧道中的翼型周围的流动，与弦雷诺数高达三百万。此外，提出了一个程序，可用于检索气泡的平均密度和分散体的平均速度和波动的测量，分别。
The behaviour of nearly neutrally buoyant tracers is studied by means of experiments with helium-filled soap bubbles and numerical simulations. The current models used for estimating the slip velocity of heavy micro particles and neutrally buoyant particles are reviewed and extended to include the effect of unsteady forces and particle Reynolds number. The particle motion is analysed via numerical simulations of a rectilinear oscillatory flow and in the flow around an airfoil within a particle flow parameter space that is typical of large-scale PIV experiments. An empirical relation is obtained that estimates the particle slip velocity, depending on the particle-to-fluid density ratio, the particle Reynolds number and frequency of the local flow fluctuations. The model developed is applied to assess the slip velocity of helium-filled soap bubbles in a large-scale experiment conducted at the German–Dutch wind (DNW) tunnels in the flow around an airfoil, with chord Reynolds numbers up to three millions. Furthermore, a procedure is proposed that can be used to retrieve the bubbles mean density and dispersion from measurements of mean velocity and fluctuations, respectively.