Abstract
A jet was formed by issuing 0.9 wt% water solution of fluorescent dye impulsively with velocity UN=7.2 cm/s from a round nozzle with a diameter d=17.95 mm into otherwise quiescent water. The cross section including the jet axis was visualized by scanning a laser beam. A sequence of photographs was taken with an interval of 0.25 s in a run from the start of the jet. The area of a photograph was divided into 256×256 meshes and their brightness were converted into digital values, from which the characteristics of turbulence in the jet were investigated quantitatively. The image processing developed in this work provides an effective method to analyse spacial structure of turbulence in unsteady flows.
