Performance of PIV and PTV for granular flow measurements
Performance of PIV and PTV for granular flow measurements
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DOI：
10.1007/s10035-017-0730-9
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发表时间：
2017-08-01
期刊：
影响因子：
2.4
通讯作者：
Shepley, Paul
中科院分区：
文献类型：
--
作者：
Gollin, Devis;Brevis, Wernher;Shepley, Paul
随着测量实验颗粒流的工具和技术变得越来越复杂，需要严格评估所用方法的有效性。本文严格评估了粒子图像测速 (PIV) 和粒子跟踪测速 (PTV) 在测量颗粒流动特性方面的性能。在简要回顾 PIV 和 PTV 技术之后，我们描述了这两种方法的应用中产生的最常见的误差源。对于 PTV，使用一系列圆周运动的受控实验来说明与粒子质心不确定性和粒子轨迹的线性近似相关的误差。然后，通过对沿着倾斜溜槽几何结构的干燥单分散颗粒流的实验来检查这些误差的影响。将结果与 PIV 分析的结果进行比较，其中误差受询问区域大小的影响。虽然两种技术估计的速度剖面显示出很强的一致性，但二阶统计数据，例如颗粒温度，显示出截然不同的轮廓。我们展示了采样间隔或帧速率的选择如何影响颗粒温度的大小和 PTV 情况下确定的轮廓形状。此外，在直接测量时，PIV 确定的颗粒温度幅度往往要低得多，或者在理论上按比例缩放时，其确定的颗粒温度幅度往往比相同测试中的 PTV 确定的颗粒温度幅度要低得多，尽管轮廓的形状对帧速率不太敏感。最后，我们展示了在侧壁获得的固体浓度分布，并检查它们与确定的剪切速率和颗粒温度分布的关系。
As tools and techniques to measure experimental granular flows become increasingly sophisticated, there is a need to rigorously assess the validity of the approaches used. This paper critically assesses the performance of particle image velocimetry (PIV) and particle tracking velocimetry (PTV) for the measurement of granular flowproperties. After a brief review of the PIV and PTV techniques, we describe the most common sources of error arising from the applications of these two methods. For PTV, a series of controlled experiments of a circular motion is used to illustrate the errors associated with the particle centroid uncertainties and the linear approximation of particle trajectories. The influence of these errors is then examined in experiments on dry monodisperse granular flows down an inclined chute geometry. The results are compared to those from PIV analysis in which errors are influenced by the size of the interrogation region. While velocity profiles estimated by the two techniques show strong agreement, second order statistics, e.g. the granular temperature, display very different profiles. We show how the choice of the sampling interval, or frame rate, affects both the magnitude of granular temperature and the profile shape determined in the case of PTV. In addition, the determined magnitudes of granular temperature from PIV tends to be considerably lower when directly measured or largely overestimated when theoretically scaled than those of PTV for the same tests, though the shape of the profiles is less sensitive to frame rate. We finally present solid concentration profiles obtained at the sidewalls and and examine their relationship to the determined shear rate and granular temperature profiles.