Optical flow diagnostics

(Stereoscopic) Particle Image Velocimetry:

  • Provides in-plane components of velocity in planar cross-section of flow when using 1 camera; also out-of-plane velocity when using 2 cameras.
  • In our lab applied in many turbulent flows, in particular with rotation. Also in shallow-layer flows and in the wind tunnel.
  • Dual-cavity pulsed Nd:YAG laser with dual-exposure PIV cameras.

3D Particle Tracking Velocimetry:

  • Tracking of tracer particles in a 3D volume with (typically) 4 cameras; provides full volumetric flow velocity measurement.
  • Tracking applied in rotating turbulent flows, convection-driven flow, but also in 3D laminar mixing experiments.
  • Even used to track water droplets in turbulent airflow.
  • Pulsed LED arrays for volumetric illumination; camera sets with framerates of 30 Hz and of 1 kHz.

Selection of publications involving these techniques:

Rajaei, H., Joshi, P.R., Alards, K.M.J., Kunnen, R.P.J., Toschi, F. & Clercx, H.J.H. (2016). Transitions in turbulent rotating convection: A Lagrangian perspective. Physical Review E, 93(4):043129.

Bertens, G., Voort, van der, D.D., Bocanegra Evans, H. & Water, van de, W. (2015). Large-eddy estimate of the turbulent dissipation rate using PIV. Experiments in Fluids, 56, 89-1/9.

Castello, Del, L. & Clercx, H.J.H. (2011). Lagrangian acceleration of passive tracers in statistically steady rotating turbulence. Physical Review Letters, 107(21):214502.

Bokhoven, van, L.J.A., Clercx, H.J.H., Heijst, van, G.J.F. & Trieling, R.R. (2009). Experiments on rapidly rotating turbulent flows. Physics of Fluids, 21(9):096601.

Akkermans, R.A.D., Cieslik, A.R., Kamp, L.P.J., Trieling, R.R., Clercx, H.J.H. & Heijst, van, G.J.F. (2008). The three-dimensional structure of an electromagnetically generated dipolar vortex in a shallow fluid layer. Physics of Fluids, 20(11):116601.