Velocity measurements for flows around micro-cylinder array based on image overlapping

In this study, the influence of depth of correlation (DOC) on the micro-PIV measurement is analyzed. The method of image overlapping under the low particle density condition can decrease DOC and improve the velocity measurement accuracy. This method is applied to the velocity measurements on multiple fluid planes for the flow around a micro-cylinder array under eight Reynolds numbers from 0.8 to 3.6, and the spatial averaged velocities (SAVs) are calculated based on the velocities. In order to analyze the measurement accuracy, the velocities and SAVs resulting from the method of image overlapping are compared to those obtained by the method of average cross-correlation. The results indicate that of the image overlapping is a more reasonable method under the low particle density condition. The average pseudo-slip velocity decreases by 22.7% for the bottom surface and 17.2% for the top, respectively, and the average peak velocity increases by about 5.2%.