Suppression of planar PIV errors due to particle intensity variations

One of the major sources of error in planar PIV is due to particle intensity variations when e.g. particles with out-of-plane motion change their intensity or disappear completely. The same effect comes e.g. from different laser beam profiles for the first and second laser pulse or from non-spherical rotating particles changing reflectivity. It has been shown that the error due to this effect can be as large as 0.05 to 0.1 pixel for typical out-of-plane displacements. The paper introduces a method to suppress the influence of this error source based on selective pixel weighting using local correlation values over a 3×3 pixel area. The method has been applied to synthetic data and a moving glass block with markers. In most cases a substantial reduction in error of 20 to 50% has been achieved