Near field vortex dynamics in axially forced, co-flowing jets:: quantitative description of a low-frequency configuration

This work presents an experimental study of the vortex structures that appear in the shear layer of co-flowing water jets subjected to a strong axial forcing. Quantitative, forcing-phase-locked measurements of the velocity in the near field were obtained using two-component Particle Image Velocimetry (PIV). Two-dimensional vorticity, strain and pressure fields were obtained from these data. Also, some information could be obtained about the azimuthal velocity. The data validates a previous [Rodriguez et al., European J. Mech. B. Fluids 20 (5) (2001) 673-698] qualitative description of the near field vortex dynamics in a highly forced flow; based in inviscid mechanisms, that was supported in low Re (Re-D = 440) experiments The experiments presented here show the vortex dynamics is similar for higher Reynolds numbers (Re-D approximate to 7000) and provides quantitative information of the interesting fields. Also, the present work extends the description to low forcing amplitude cases. (C) 2002 Editions scientifiques et medicales Elsevier SAS. All rights reserved.