Particle Image Velocimetry
Measure time-resolved velocity fields, flow direction, turbulence, and transient fluid behavior using seeded tracer particles, pulsed laser illumination, and synchronized high-speed imaging.
Quantitative Flow Visualization
Particle Image Velocimetry, commonly called PIV, is an optical measurement technique widely used in fluid dynamics research. It provides detailed measurements of velocity, direction, vectors, vorticity, turbulence, and other flow properties across a field of view.
The flow is seeded with tracer particles and illuminated using a short laser pulse or laser sheet. By comparing particle positions between precisely timed images, PIV software calculates particle displacement and converts the results into a map of velocity vectors.
Core PIV System Elements
A complete measurement system combines seeded flow, precisely timed illumination, synchronized image capture, calibration, and vector-processing software.
Tracer Particles
Small particles are introduced into the fluid and selected to follow the flow accurately without significantly altering it.
Laser Illumination
A short, intense sheet or spot pulse freezes particle motion and produces strong contrast against a dark background.
Synchronized Cameras
High-speed cameras record precisely timed particle images for planar, stereo, time-resolved, or volumetric flow analysis.
PIV Measurement Methods
The required method depends on whether the goal is planar velocity, three-component motion, microscale flow, or full volumetric measurement.
2D PIV
A single camera views a thin illuminated plane and measures two velocity components within that plane.
- One camera and one laser sheet
- Two in-plane velocity components
- Efficient setup and calibration
- Suitable for many wind-tunnel and water-flow tests
Stereo PIV
Two synchronized cameras view the same laser sheet from different angles to calculate three velocity components.
- Two calibrated camera views
- In-plane and out-of-plane velocity
- Useful for complex three-component flow
- Requires precise geometry and synchronization
Micro-PIV
Microscope optics and small tracer particles are used to measure flow inside microchannels and miniaturized fluidic devices.
- High magnification and small fields of view
- Micron-scale particles and channel features
- Strong sensitivity and short exposures
- Applications in microfluidics and biotechnology
Tomographic PIV
Multiple synchronized cameras reconstruct illuminated particle distributions inside a volume to calculate three-dimensional velocity fields.
- Multiple calibrated camera views
- Three-dimensional measurement volume
- Detailed vortex and turbulent-flow analysis
- Advanced calibration and reconstruction software
Common PIV Applications
Time-resolved PIV supports research across automotive, aerospace, biotechnology, medicine, marine propulsion, electronics, and academia.
Automotive Aerodynamics
Measure wakes, underbody flow, cooling airflow, cabin ventilation, intake systems, and flow around vehicle surfaces.
Aerospace Testing
Study airfoil separation, boundary layers, transonic buffet, jets, rotor flow, propulsion, and wind-tunnel aerodynamics.
Turbulent Flow
Quantify eddies, shear layers, vorticity, velocity fluctuations, mixing, separation, and transient flow structures.
Multiphase Flow
Analyze liquid-gas systems, bubbly flow, sprays, particles, cavitation, and interactions between continuous and dispersed phases.
Marine Propulsion
Measure propeller wakes, cavitation, jets, pumps, underwater vehicles, and flow around marine structures.
Thermal Management
Visualize cooling airflow, liquid cooling, electronics flow paths, heat exchangers, and buoyancy-driven circulation.
Typical PIV Workflow
Reliable velocity data depends on particle selection, laser-sheet alignment, calibration, interframe timing, synchronized recording, and appropriate vector-processing parameters.
Featured Research Examples
Research examples retained from Photron’s existing Particle Image Velocimetry page.
Phase Image-Based Particle Tracking
A three-dimensional particle-detection method using phase images was developed for particle tracking velocimetry and demonstrated through Poiseuille-flow measurement.
Sound Waves and Transonic Buffet Flow
Time-resolved tomographic PIV and unsteady pressure measurements were used to study how artificially introduced sound waves affect buffet flow over a supercritical airfoil.
Read more →Annular-Channel Multiphase Flow
PIV, bubble imaging, and particle tracking were combined to measure continuous-phase velocity, turbulent characteristics, bubble size, position, and rising velocity.
Read more →Selecting a Camera for PIV
The correct system depends on particle-image size, flow velocity, field of view, laser energy, interframe timing, repetition rate, measurement duration, and whether multiple synchronized camera views are required.
Need help configuring a PIV system?
Share your flow speed, field of view, particle size, laser system, frame rate, interframe-time requirement, and PIV method with Photron.