Efficient second-order PIV algorithm using full image deformation

Abstract

The algorithm used by DLR for the PIV-Challenges 2003 and 2005 features a combination of pyramid-based grid refinement (multi-grid) and full-field image deformation and is intended to give second-order accurate displacement data. At its core a standard FFT-based correlation algorithm provides local image shift data. This displacement data is used to deform the original images after each iteration. Special emphasis was placed on striking a balance between accuracy, robustness and processing speed. The specific characteristics of this algorithm, whose flowchart is shown on the right, are explained in the following sections. Visual inspection of the processed data was found very useful in the proper choice of PIV processing parameters and optional image filtering. The most advanced schemes do not necessarily achieve the highest precision as they may introduce undesired artifacts.