粒子图像强度和图像预处理对显微PIV中相关深度影响的研究

The depth of correlation (DOC) is an experimental parameter, introduced to quantify the thickness of the measurement volume and thus the depth resolution in microscopic particle image velocimetry (μPIV). The theory developed to estimate the value of the DOC relies on some approximations that are not always verified in actual experiments, such as the use of a Gaussian function to describe the particle image intensity distribution. In addition, the application of image pre-processing, widely used in μPIV evaluations, significantly contributes to modify the actual size of the DOC. In the presented paper, the effect of real particle image intensity distribution and image pre-processing on the thickness of the measurement volume is investigated. Furthermore, the bias error induced by the DOC in μPIV measurements is qualified on a Poiseuille flow in a microchannel. Results and guidelines to appropriately reduce the bias error due to DOC are discussed.