Partikeltracking

Partikeltracking, also known as particle tracking velocimetry (PTV), is an experimental technique used to measure velocity fields in fluids. It involves introducing small, tracer particles into the fluid and then illuminating them with a light source, typically a laser sheet. High-speed cameras are used to capture images of the particles at different time instances. By analyzing the displacement of individual particles between successive images, their trajectories can be determined. From these trajectories, the velocity of the fluid at the particle's location can be calculated.

The fundamental principle of particle tracking relies on the assumption that the tracer particles faithfully follow the fluid motion. This requires careful selection of particle properties, such as size, density, and material, to ensure they are small and light enough to be advected by the flow without significant slip. Common tracer particles include small spheres made of polystyrene, glass, or hollow ceramic, with sizes typically ranging from a few micrometers to a few tens of micrometers.

Particle tracking velocimetry can be broadly categorized into two main types: tomographic PTV and planar PTV. Planar PTV analyzes the motion of particles in a 2D plane, usually defined by the laser sheet. Tomographic PTV, on the other hand, extends this to three dimensions by using multiple cameras to reconstruct the particle positions in a volume. This provides a more comprehensive understanding of complex three-dimensional flow structures.

Applications of particle tracking are diverse, spanning fields such as fluid mechanics research, aerodynamics, hydrodynamics, biomedical engineering (e.g., blood flow analysis), environmental studies (e.g., pollutant dispersion), and industrial process monitoring. The technique offers high spatial resolution and can capture instantaneous velocity fields, providing valuable insights into turbulent flows, vortex dynamics, and other intricate fluid phenomena.