Automatic eduction and statistical analysis of coherent structures in the wall region of a confined plane turbulent impinging jet

• Published in: Experiments in fluids 2006-07, Vol.41 (1), p.35-55
• Main Authors: PAVAGEAU, M, LOUBIERE, K, GUPTA, S
• Format: Article
• Language: English
• Subjects: Algorithms; Coherence; Engineering Sciences; Exact sciences and technology; Fluid dynamics; Fluid flow; Fundamental areas of phenomenology (including applications); Instrumentation for fluid dynamics; Jets; Marine; Physics; Planes; Statistical analysis; Turbulence; Turbulent flow; Turbulent flows, convection, and heat transfer
• ISSN: 0723-4864; 1432-1114
• DOI: 10.1007/s00348-006-0144-7

This paper describes a vortex detection algorithm used to expose and statistically characterize the coherent flow patterns observable in the velocity vector fields measured by particle image velocimetry in the impingement region of air curtains. The philosophy and the architecture of this algorithm are presented. Its strengths and weaknesses are discussed. The results of a parametrical analysis performed to assess the variability of the response of our algorithm to the three user-specified parameters in our eduction scheme are reviewed. The technique is illustrated in the case of a plane turbulent impinging twin-jet with an opening ratio of 10. The corresponding jet Reynolds number, based on the initial mean flow velocity U 0 and the jet width e, is 14,000. The results of a statistical analysis of the size, shape, spatial distribution and energetic content of the coherent eddy structures detected in the impingement region of this test flow are provided. Although many questions remain open, new insights into the way these structures might form, organise and evolve are given. Relevant results provide an original picture of the plane turbulent impinging jet.