bildevelocimetry

Particle Image Velocimetry, often abbreviated as PIV, is an optical measurement technique used for obtaining instantaneous velocity field measurements in fluids. It involves seeding the fluid with small tracer particles that are assumed to follow the fluid motion. A laser sheet illuminates a plane within the fluid, and two consecutive images of the illuminated particles are captured by a camera. The time interval between the two images is precisely known.

The captured images are then processed by dividing them into small interrogation windows. By tracking the displacement of particle patterns within these windows between the two images, the average velocity within each window can be calculated. This process is repeated for all interrogation windows to generate a velocity vector map for the entire illuminated plane. PIV is a non-intrusive technique, meaning it does not significantly disturb the flow being measured.

PIV has found widespread applications in various fields, including aerodynamics, hydrodynamics, combustion research, and microfluidics. It provides detailed spatial information about fluid flow that is often difficult to obtain with other measurement methods. Advanced PIV techniques, such as stereoscopic PIV and tomographic PIV, can even measure three-dimensional velocity fields. The accuracy of PIV measurements depends on factors like particle seeding density, image resolution, and the accuracy of the time interval.