Research on flow velocity field in jagged micro-channel with micro-PIV

With the micro-fluidic particle image velocimetry technique, the flow was measured in both of cusp and fillet jagged micro-channels with a cross section of 800 μm×800 μm at Re=150. Deionized water with 3 μm-diameter fluorescent particles inside was adopted in the micro-channels. The distinct images were obtained with a 10-fold microscope and 14-bit CCD camera system. The influence of Brownian motion was eliminated by averaging obtained images of the particles. Filter lens were used to improve the signal-to-noise ratio of the images. The experimental results indicate that the flow patterns in both jagged micro-channels are similar to each other. There is a low velocity vortex cavity at the swerving inside for both the fillet jagged micro-channel and the cusp jagged micro-channel, and the former vortex cavity is greater than the latter one. Moreover, at the jag peak of the cusp jagged micro-channel, there exist a big intact vortex and a superposition vortex in the opposite direction with lower velocity and unsteady structure. The impure substance in the low-velocity region is easier to deposit and form block, leading to the structure change of the micro-channels.