Applications of DDPIV to Studies Associated with Road Vehicles

The quantification of experimental flows is a problem that poses several challenges, the most obvious of which is how to extract motion from an "invisible" phenomenon. In general, flows can be analyzed through a sequence of still images (Singh 1991). For example, the motion of patterns generated by dye, clouds or particles can be used to obtain such a time sequence of still images. The main problem with using a continuous-intensity pattern, generated by scalar fields (e.g., dye patterns), is that it must be somehow discretized and contain variations of intensity at all scales before mean and turbulent velocity information can be obtained (Pearlstein and Carpenter 1995). In this respect, the discrete nature of images generated by seeding particles has made particle tracking the method of choice for whole field velocimetry. Displacement and, thus, velocity information can be extracted through statistical methods and other methods such as particle tracking. The spatial resolution of this method depends on the number density of the particles.