1. Particle Image Velocimetry (PIV) Introduction
Imaging Techniques for Flow and Motion Measurement
Lecture 3
Particle Image Velocimetry (PIV) Introduction
Lichuan Gui University of Mississippi 2011

2. Particle Image Velocimetry (PIV)
Optical, non- or minimally-intrusive, fluid flow measurement technique;
Instantaneous flow measurements in two-dimensional (2D) area or three-dimensional (3D) volume field of views;
Basic procedure of PIV
Flow visualization
Flow field seeded with small tracer particles
Particles usually illuminated by a laser light sheet
Image recording
Particle images captured by an imaging system
Image evaluation
Usually using auto- or cross-correlation algorithm

3. Flow visualization with small particles
Stroboscopic illumination techniques

4. Flow visualization with small particles
Multiple exposed particle images
Oil drop in laminar pipe flow (Air)
Solid particles in water flow

5. 2D & 2-component PIV Systems
CW laser with high-speed photo or video camera

6. 2D & 2-component PIV Systems
Consecutive singly exposed PIV recordings
Fluorescent particles in a microdevice
0.540.41 mm2, 30 fps
Smoke flow in air
0.50.5 mm2, 500 fps

7. 2D & 2-component PIV Systems
Standard 2D PIV
Light
sheet
t=t0
Lens
Measurement
volume
Laser
t=t0
Image #1
Single exposed recording
Fluid flow seeded with
small tracer particles
Double exposed recording
Exposure #1
Lens system & Camera

8. 2D & 2-component PIV Systems
Standard 2D PIV
Light
sheet
t=t0+t
Lens
Measurement
volume
Laser
Image #1
t=t0
Fluid flow seeded with
small tracer particles
t=t0+t
Image #2
Exposure #2
Exposure #1
Lens system & Camera
Single exposed recording
Double exposed recording

9. 2D & 2-component PIV Systems
Velocity determination with standard 2D PIV
Image plane
Objective Lens
Laser light sheet
Scale factor: M=L/L’
Time interval: t
Velocity: V=S/t=M·S’/ t
Laser light sheet
Image plane
Objective Lens S S’ L L’

10. Micro-scale PIV (MPIV) System
Nd:YAG Laser
Micro Device
Flow in
Flow out
Glass
cover
CCD Camera
(1280x1024 pixels)
Beam
Expander
Epi-fluorescent
Prism / Filter Cube
Microscope
Nd:YAG LASER
MICROSCOPE
BEAM EXPANDER
CCD CAMERA
MCROFLUIDIC DEVICE
Flood Illumination
l=532 nm
Focal Plane
l = 610 nm
Micro-Fluidics Lab Purdue University
Micro-PIV image pair

11. 3D or 3-component PIV Systems
Stereo PIV
3 velocity components in a plane
Two cameras
Holographic PIV
3 velocity components in a 3 dimensional volume
Complex and precise illumination
Defocusing PIV (Pereira et al. 2000)
Allow images to become defocused
Single camera/ color CCD, particle image tracking
Multiple-sheet PIV (Raffel et al.,1995 )
Multiple laser light sheet, single camera
3D scanning PIV (Brücker, 1997)
Scanning a 3D volume with a laser beam
Single high speed camera

12. 3D or 3-component PIV Systems
Stereo PIV configurations
a. Translation systems
(lateral displacement)
b. Rotational systems
(angular displacement) Scheimpflug condition

13. 3D or 3-component PIV Systems
Stereo PIV data reduction
Translation systems (Mn=di/do)

14. 3D or 3-component PIV Systems
Stereo PIV data reduction
Rotational system (Mnconstant)

15. Holographic PIV (HPIV) System
Holographic diagnostics of a 3D particle filed
Hologram recording
Hologram reconstruction

16. Holographic PIV (HPIV) System
Holographic recording of particles
Interference pattern in a HPIV recording

17. Holographic PIV (HPIV) System
Reconstructed HPIV particle images

18. Holographic PIV (HPIV) System
Example of HPIV system (recording)

19. Holographic PIV (HPIV) System
Example of HPIV system (reconstruction)

20. Homework Practice with EDPIV software
Read EDPIV help manual page to know details in “Raw Image Format” window
Open images in application example #0 with EDPIV and look at image details.
EDPIV software and sample images are available at