Three-dimensional flow velocity and wall shear stress distribution measurement on a micropillar-arrayed surface using astigmatism PTV to understand the influence of microstructures on the flow field

Abstract

In this study, the influence of the microstructure in a microchannel on the three-dimensional (3D) flow field and shear stress distribution on the wall was investigated with 3D velocity measurement method. In a micro-total analysis system or a lab-on-a-chip application, the control of the flow is necessary. Thus, microstructures are often applied to the fluidic system for passive flow control. However, the flow field which interacts with microstructures becomes complicated three-dimensionally. The 3D measurement of such microfluidic flow would give insight on the interaction of the flow with the structures and be also useful for other applications. In this study, micropillar array was introduced in a microchannel and we investigated the influence of the micropillar on the 3D flow field by the astigmatism particle tracking velocimetry which enables to determine three-dimensional and three-component velocity by single-viewing. Furthermore, the wall shear stress distribution was also investigated. From measurement results, it was confirmed that the pillar changes the wall shear stress distribution and 3D velocity distribution. Compared to a flat channel (no-pillar array), the wall shear stress in our channel varied spatially in a range of approximately − 80 to + 20%. Moreover, we also conducted a numerical simulation to consolidate the measurement results.