Dataset: Burgers vortex velocity fields

The tomographic particle image velocimetry (tomographic PIV) technique was used to measure the three-dimensional flow field (Elsinga et al., 2006) and to quantitatively confirm that it matches the target parameters of small-scale eddies in copepod habitats. The tomographic PIV technique reconstructed the volumetric position of small particles suspended in the fluid, the position of which was imaged by collecting scattered laser light via four cameras simultaneously. Particle displacements were calculated via cross-correlation of particle locations in consecutive volumetric reconstructions in order to measure the local three-dimensional velocity vector. Three-dimensional flow measurements were required for this flow since the local velocity vector included three components of motion and the flow field varied in three coordinate directions.

The tomographic PIV system (Murphy et al., 2012) used four high-resolution (Phantom v210, 1280 × 800 pixels), cameras to measure flow fields at the scale of the copepod. Images were captured digitally at a rate of 24 frames per second. To resolve the small length scales in this study, a 105 mm focal length lens (Nikon) was used for each camera. Scheimpflug mounts were used to change the orientation of the lens to correct the plane of focus on the cameras (Murphy et al., 2012). Orgasol polyamide powder (20 micron diameter; specific weight of 1.03 g cm-3; Arkema group) tracked the fluid motion within the tank. An infrared laser (808 nm wavelength) was used to illuminate the tracer particles. Experiments were performed in a dark room to eliminate any light outside the control volume that could increase the level of error in the flow measurements.