Proceesing techniques: image plane and Fourier plane.

Statistical analysis of PIV image data can be performed by either image plane analysis or Fourier transform plane analysis of fringes. A detailed theoretical analysis of the interrogation procedure for images and fringes is presented. The two-dimensional spatial correlation of the images of particles in high image density PIV produces a function that determines the mean displacement of the images in an interrogation spot, and hence the mean fluid velocity in the volume. Similar results can be obtained from the 2-D Fourier transform of the Young's fringe pattern. Alternatively fringes can be dealt with directly. Maximum information is extracted from the fringes using the Fourier transform approach. (from authors' abstract)