PIV is an optical method of flow visualization used in education and research. It is used to obtain instantaneous velocity measurements and related properties in fluids. The fluid is seeded with tracer particles which, for sufficiently small particles, are assumed to faithfully follow the flow dynamics.
The fluid with entrained particles is illuminated by pulsed laser light-sheet synchronized with cameras producing images, so particles are visible within specific illuminated area. The motion of the seeding particles is used to calculate speed and direction (the velocity field) of the flow being studied in 2D, 3D and Volume.