Particle-tracking velocimetry with new algorithms

New algorithms for particle-tracking velocimetry are proposed and tested with typical particle images showing two-dimensional fluid flows. There are new ideas not only in the algorithm of the particle tracking itself but also in that of the individual-particle detection. The performance of the particle tracking is much improved by the new relaxation method and that of the individual-particle detection by the use of the dynamic threshold-binarization method. The special concern of the authors about the new algorithms is the applicability of particle-tracking velocimetry to high-density particle images, contrary to what is usually believed regarding this type of particle-imaging velocimetry. These new algorithms are first tested in synthetic images with a variety of particle parameters and then in other types of experimental visualizations showing jet and wake flows.