‘Shake The Box’: Lagrangian particle tracking in densely seeded flows at high spatial resolution

Kurzfassung

Great progress has been made in the field of optical and particle based measurement techniques for (turbulent) flow investigations in the past few decades. The rise of digital high- frame rate and dual-frame cameras and powerful pulse lasers enabled a special breakthrough for PIV and PTV measurement techniques. PIV delivers spatially well resolved velocity vectors in a 2D- or 3Ddomain in an Eulerian frame of reference and thus the velocity gradient tensor, while PTV determines Lagrangian particle tracks with a limited spatial density, but high accuracy of the particle velocity estimation due to temporal filtering by appropriate (polynomial) fitting functions. Therefore, from properly designed 3D PTV experiments high-resolution turbulence statistics can be calculated including e.g. mean profiles or the Reynolds stress tensor. The newly developed 4D PTV technique Shake The Box (STB) has been introduced recently (Schanz et al. 2013b, Schanz et al. 2014) and is capable of delivering highly accurate and dense velocity information in a volume of the flow by reconstructing a large amount of Lagrangian particle tracks from a time series of particle images. The main advantages of such data for turbulence (shear) flow research are the possibility to bridge between Eulerian and Lagrangian frames of reference and to provide relevant measures for local and global velocity statistics at high spatial and temporal resolution.