Here, we introduce Streamline Image Velocimetry, a method to derive fluid velocity fields in fully developed laminar flow from long-exposure images of streamlines. Streamlines confine streamtubes, in which the volumetric flow is constant for incompressible fluid. Using an explicit analytical solution as a boundary condition, velocity fields and emerging properties such as shear force and pressure can be quantified throughout. Numerical and experimental validations show a high correlation between anticipated and measured results, with R2 > 0.91. We report spatial resolution of 2 μm in a flow rate of 0.15 m/s, resolution that can only be achieved with 75 kHz frame rate in traditional particle tracking velocimetry.
Bibliographical noteFunding Information:
The authors would like to thank Prof. Mehmet Toner and Dr. Grace Chen for sharing streamline images. This work was supported by the European Research Council Starting Grant (TMIHCV 242699) and by International Re-integration Grant (MICROLIVER 248417). Resources were also provided by National Institute of Diabetes and Digestive and Kidney Diseases (K01DK080241). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.