The department of building physics has various measurement methods at its disposal with which air flows within double facade systems or in large rooms can be visualised and analysed.
Particle Image Velocimetry (PIV)
Particle Image Velocimetry is a method for non-invasive measurement of flow processes. Small particles in the form of helium-filled soap bubbles (bubble diameter approx. 1-2 mm) or oil mist (particle size in the um range) are mixed into the air. The individual particle movements are recorded with a high-resolution CCD camera. The particle or particle pattern movements of the particles are evaluated and vectorized via image processing.
Particle Tracking Velocimetry (PTV)
While Particle Image Velocimetry (PIV) is based on the pattern recognition of particles and their "migration" within several image sequences, the Particle Tracking Velocimetry (PTV) method offers the advantage of tracking individual particles over a longer period of time and a greater distance (over all spatial dimensions). In contrast to the PIV method described above, the tracking method uses balloons as particles instead of soap bubbles. These were also filled with a helium-air mixture in such a way that the weight of the balloon envelope was just lifted. Two synchronized, spatially offset standard cameras are sufficient for the 3D stereo tracking method.