As part of our ongoing development of the Boldrewood towing tank we’ve spent a week carrying out the International Towing Tank Conference‘s recommended Particle Image Velocimetry (PIV) benchmark case. PIV technique allows the velocity field to be measured across a two -dimensional plane created by a laser sheet. The tank is seeded with small reflective particles and two photos are taken a short time interval apart. Image processing allows the velocity field within a high resolution underwater camera’s image frame to be measured.

In these tests a rig was built to allow a flat plate to be towed at an angle of attack creating a strong tip vortex. The PIV measurements allow the location and strength of the vortex to be obtained experimentally. The tank test has to be run in the dark with the use of special protective goggles when observing the tests.

The tests for the calibration are carried out at low speed of 0.4 m/s with even the carriage light switch off and just the faint glow of the data acquisition computer screens

Thanks to the team lead by Magnus with support from Melike, James and David. Funding the LaVision PIV system came through the EPSRC funded National Wind Tunnel Facility