PIVtekniikka

PIVtekniikka, short for Particle Image Velocimetry, is an optical measurement technique used to obtain instantaneous velocity field measurements in fluids. It is a non-intrusive method, meaning it does not disturb the flow being studied. The fundamental principle of PIV involves seeding the fluid with small tracer particles that are assumed to follow the flow accurately.

The process begins by illuminating a plane within the fluid with a thin sheet of light, typically from a pulsed laser. This light sheet creates a two-dimensional slice of the flow. A high-resolution camera is positioned perpendicular to the light sheet to capture images of the illuminated tracer particles. The laser is pulsed twice in rapid succession, with a precisely known time interval between pulses.

The camera captures two images, one for each laser pulse. These images record the positions of the tracer particles at two different moments in time. Image processing software then divides these images into small interrogation windows. By tracking the displacement of particle patterns within corresponding interrogation windows in the two images, the software calculates the average velocity vector for each window.

The result is a vector map representing the instantaneous velocity field within the illuminated plane. PIVtekniikka is widely used in various fields, including aerodynamics, hydrodynamics, combustion research, and biomedical engineering, to study complex flow phenomena, validate computational fluid dynamics models, and gain insights into fluid behavior.