PIVtekniikoita

PIVtekniikoita, or Particle Image Velocimetry techniques, are non-intrusive optical methods used to measure fluid flow. These techniques allow for the simultaneous determination of the velocity field in a two-dimensional plane or a three-dimensional volume. PIV works by seeding the fluid with small, neutrally buoyant tracer particles that follow the flow.

A laser sheet illuminates these particles in a thin cross-section of the flow. A camera, typically positioned perpendicular to the laser sheet, captures images of the particles at two distinct moments in time, separated by a very short interval. Image processing software then analyzes these pairs of images. By dividing the images into small interrogation windows and tracking the displacement of particle groups within these windows over the known time interval, the velocity vectors for each window can be calculated.

There are several variations of PIV. Planar PIV is the most common, providing velocity measurements in a 2D plane. Stereoscopic PIV uses two cameras to capture the flow from different angles, allowing for the reconstruction of the three velocity components in a 2D plane. Tomographic PIV employs multiple cameras to reconstruct the velocity field in a 3D volume. Time-resolved PIV (TR-PIV) uses high-speed cameras to capture a rapid sequence of images, enabling the study of unsteady and turbulent flows. PIV is widely applied in fields such as aerodynamics, hydrodynamics, combustion research, and biomedical engineering.