Particle Image velocimetry (PIV)
PIV principle
Particle Image Velocimetry is a method to determine the velocities in a fluid. The flow measurement with PIV is based on the measurements of the displacement (∆x) of a particle in a target plane between two successive light pulses with time delay (∆t). The flow is seeded with particles and the target plane is illuminated with a light sheet. The particle positions are recorded by two special digital cameras. Special image processing software analyses the movements of the group of particles in subsections of the PIV-image using correlation techniques. By using two cameras in a stereoscopic arrangement the instantaneous three velocity components are derived in the measuring plane.

PIV set-up PIV set-up
MARIN PIV system
MARIN acquired a DANTEC stereo-PIV system which has been operational since September 2009. The power of the lasers is 200 mJ and 4M CCD cameras are mounted inside probe. In all configurations the generation of the laser sheet and cameras are combined in one probe guaranteeing one rigid structure.

This system is designed to operate in MARIN’s Deep Water Towing Tank to perform the following tests:
• Wake field measurements
• Appendage alignment
• Full 3D hull scans
• Detailed scans of propulsion units
• Offshore tests: VIV, thruster interactions
• Specials...

The dimension of the measurement plane in the standard configuration measures approximately 320 mm by 230 mm with up to 12000 velocity measurement points within this field.

MARIN PIV record
Thruster interaction research
To study the interactions of a thruster with a hull and pontoon, PIV measurements have been conducted on an open water thruster, hull with thruster and hull with thruster and pontoon.

Propeller optimisation
The in- and outflow of a propeller can be studied with PIV. The results are valuable information in propeller optimisation studies.

wake flow
Wake flow
Measurements have been conducted in the wake field of an LNG carrier. The results are compared with pitot and CFD measurements and a close agreement has been observed.

Rink Hallmann, Project Manager Ships
T +31 317 493 485

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