Particle Image Velocimetry (PIV) is a long-standing and versatile technique for measuring flow across fields. This optical technique, frequently used in education and research, measures the velocity field of a region within the flow simultaneously. Light scattering particles are added while a laser beam formed into a light sheet illuminates the particles. PIV can provide a quantitative map that gives a more detailed physical explanation of particles in motion.

PIV is used to evaluate an entire plane, by detecting the local velocity of a small area of motion, by statistical means, not the specific velocity of single tracer particles. PTV, or Particle Tracking Velocity, on the other hand, is used to resolve individual particles in two consecutive frames and is better suited for areas with large velocity gradients.

In the past decade, PIV has carved out a niche for itself in laboratory and field research in a variety of fields. Most recently it has been used to study the flow of objects as diverse as:

• Pedestrian traffic patterns in high-density events

• Nanoparticle flow in a 400nm nanochannel

• Hydrodynamic evaluation of aortic cardiopulmonary bypass

In object research PIV allows us to better understand and address the impacts, efficacy, and safety in a wide range of applications.

For objects varied in size and speed, experiment design is critical. PIV systems include:

• Digital camera: typically charge-coupled device to allow recording of a double image within microsections, though CMOS cameras are becoming a more frequent solution.

• Pulsed laser: Typically frequency-doubled Nd:YAG or Nd:YLF green light lasers. It requires sufficient energy density per pulse to illuminate particles in the flow.

• Light-sheet optics

PIV systems are now commercially available, sometimes bundled with 2D software for correlation and background correction, but many experiments demand a custom approach, often due to:

• Dense clustering of particles, requiring higher timing precision

• Interest in 3D imaging, for depth of field or other new data

• Power and brightness requirements

Customizing PIV Systems

Many researchers prefer to build their own PIV system to allow for precision control of their experiment parameters. Quantum Composers synchronizers for PIV, when paired with the Jewel DPSS laser, allow for high accuracy in determining the velocity of the fluid in PIV analysis. Quantum Composers Precision Pulse Generators utilize programmable modes and channels with low jitter, up to 250ps timing resolution, and computer interface options.