Fluorescent streak velocimetry of non-Newtonian fluids

Here, we demonstrate how fluorescent streak velocimetry can be used to characterize flow in non-Newtonian fluids. By seeding a fluid with 2 μm colloids and imaging its flow using long exposure times (20-100 ms), we generate data which encodes information about flow velocity and acceleration in individual images. To analyze these images, we have created a user-friendly and open-source computational package. We demonstrate this technique by characterizing the channel flow profiles of several non-Newtonion fluids: micellar Cetylpyridinium Chloride solution, Carbopol 940, and Polyethylene Glycol. Our measurement resolution is sufficient to distinguish the distinct non-Newtonian flow profiles from each other and from the Newtonian profile. We will also present results of this method from more complex geometries, where significant acceleration is created due to a modified channel geometry.