Application of the vortex identification algorithms in the study of the shear layer in a 3/4 open jet automotive wind tunnel
By means of particle image velocimetry(PIV) measurements, this paper uses vortex identification algorithms to find and analyze the coherent structures in the shear layer region. The experiment was carried out in a 1:15 scaled 3/4 open jet automotive wind tunnel with a high Reynolds number（about 10^6）. The proper orthogonal decomposition(POD) is used to process the PIV experimental data, for reconstructing the velocity fields. Based on the vortex identification functions, the locations of the center, the rotation direction and the radius of vortex can be computed. Furthermore, this paper uses the statistical method to study the regularities of distribution of these vortexes, in a two-dimensional plane, and identify the vortex pairing process in the shear layer region. This paper also chooses different vortex identification algorithms to find the most accurate and suitable algorithms.