Automatic eduction and statistical analysis of coherent structures in the wall region of a confine plane

摘要

This paper describes a vortex detection algorithm used to expose and statistically characterize theudcoherent flow patterns observable in the velocity vector fields measured by Particle ImageudVelocimetry (PIV) in the impingement region of air curtains. The philosophy and the architecture ofudthis algorithm are presented. Its strengths and weaknesses are discussed. The results of audparametrical analysis performed to assess the variability of the response of our algorithm to the 3uduser-specified parameters in our eduction scheme are reviewed. The technique is illustrated in theudcase of a plane turbulent impinging twin-jet with an opening ratio of 10. The corresponding jetudReynolds number, based on the initial mean flow velocity U0 and the jet width e, is 14000. Theudresults of a statistical analysis of the size, shape, spatial distribution and energetic content of theudcoherent eddy structures detected in the impingement region of this test flow are provided.udAlthough many questions remain open, new insights into the way these structures might form,udorganize and evolve are given. Relevant results provide an original picture of the plane turbulentudimpinging jet.