Time-resolved PIV of a turbulent jet

Project · Project 66

Time-resolved Particle Image Velocimetry measurements of a turbulent jet (Re = 2500), designing and executing a full experimental setup including laser sheet illumination and high-speed imaging, followed by advanced data processing and flow analysis.

Acquisition

Acquisition parameters were optimised (dt = 12.5 ms, 80 Hz) based on displacement and confidence criteria, ensuring time-resolved measurement fidelity rather than merely time-averaged statistics.

Processing

Velocity fields were reconstructed using cross-correlation techniques, and the impact of interrogation window size (DI = 128 vs 32 px) on spatial resolution was analysed, demonstrating improved capture of shear-layer structures and turbulent fluctuations with refined processing.

Horizontal and vertical velocity fields at two interrogation window sizes/assets/img/projects/piv-velocity-fields.png

Fig. 1 — U and V fields for D_I = 128 px and 32 px.

Results

Mean flow fields and Reynolds stresses were computed, identifying peak turbulence production in the shear layer and the characteristic jet entrainment behaviour.

Principal Component Analysis via SVD was then applied to extract coherent flow structures, identifying the dominant large-scale shear-layer modes, antisymmetric flapping, and higher-frequency turbulent features.

Spatial modes of the fluctuating velocity field/assets/img/projects/piv-modes.png

Fig. 2 — Spatial modes of the fluctuating velocity field, U and V components.

Read the paper →