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

Abstract 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 ≈7000) and provides quantitative information of the interesting fields. Also, the present work extends the description to low forcing amplitude cases.

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