Figure 1 illustrates the basic elements in the 2-D PIV experiment. The CCD Camera used is a 1 megapixel Dantec HiSence. The lens and filters used are from Nikon. The laser used produces a high intensity green light sheet. In order to visualise the flow field using this light sheet a green filter is used on the CCD camera to ensure that optical wavelengths in excess of approximately 540 nm are allowed to pass through. This enables a large portion of background noise caused by other light sources, for instance, to be minimised. The laser light sheet is created by combining infrared light from two cavities using a beam combiner and passing the bundle through a harmonic generator.
The seeding particles used are produced by a fog generator. The fog passes through a fan and a box with a circular outlet. The camera and laser are positioned such that the flow exiting this box is measured at close proximity. The data captured by the CCD camera is transferred to a computer where the images are post-processed using Dantec software. The correlation technique used is cross-correlation which makes use of the signal obtained from two images taken with a short time delay.