DDPIV

Defocusing digital particle imaging velocimetry (DDPIV) is a three-dimensional volumetric flow mapping technique that can measure all three components of velocity in a volume of fluid simultaneously, thus allowing for the calculation of full derivative quantities such as vorticity. In the DDPIV technique, two or more apertures are shifted away from the centerline to obtain multiple images from each scattering source (particles). The DDPIV algorithm uses the image shift caused by off-axis apertures for the measurement of the depth location of the source points. The velocity field can then be calculated from the volumetric cross-correlation of consecutive three-dimensional sets of images.