4D particle tracking velocimetry of an undular hydraulic jump

Undular hydraulic jumps are characterized by a three-dimensional flow field due to shock waves generated near the sidewalls. Basic flow properties have been described in the literature with experimental data, mostly gathered with classical sensors which provide local information only. A continuous description of the 3D flow field is still missing. In this study, instantaneous and three-dimensional velocity data in an undular jump were obtained between the inflow section and second wave crest using a volumetric particle tracking velocimetry method with high sample rates. A special feature of the tracking algorithm is its capability to process images with very high particle density yielding a highly resolved Lagrangian description of the flow. Velocity fields, turbulent kinetic energy, dissipation rates, Reynolds stresses and turbulent scales are presented for a volume of 10 cm width in cross-direction. Some differences were found when compared to data obtained with an intrusive acoustic Doppler velocimeter.