Improvement Toward High Measurement Resolution in Three-Dimensional Particle Tracking Velocimetry

Abstract

With new algorithm of 3-D particle tracking over multiple time steps, the three-dimensional particle tracking velocimetry (3-D PTV, hereafter) system originally developed by Nishino et al. [1–3] was improved in order to achieve higher measurement resolution. It newly includes three laser disc recorders and also an engineering workstation for faster data reduction. The technique tracks fine particles suspended in a flow over two to four consecutive time steps; a particle’s new position, around which a search region for tracking is defined, is estimated from the particle’s motion at the preceding time steps. With the size of the search region statistically optimized, the tracking algorithm is evaluated on the basis of modeled Lagrangian time spectra of velocity fluctuations. A computer simulation is performed to quantitatively evaluate effectiveness of the present particle tracking technique under a condition of nearly isotropic decaying turbulence.