FSVPy: A Python-based Package for Fluorescent Streak Velocimetry (FSV)

TL;DR

FSVPy is a new Python package that enables detailed local velocity measurements in fluid flows using fluorescent streak analysis, applicable to various fluids and complex flow conditions.

Contribution

This work introduces FSVPy, a Python-based tool that advances fluorescent streak velocimetry by allowing flexible, high-resolution local flow measurements in diverse fluid systems.

Findings

Successfully characterized flow profiles of non-Newtonian fluids.

Demonstrated ability to analyze complex micro-scale flow features.

Extracted position-specific velocities from variable streak intensities.

Abstract

Predictive constitutive equations that connect easy-to-measure transport properties (e.g., viscosity and conductivity) with system performance variables (e.g., power consumption and efficiency) are needed to design advanced thermal and electrical systems. In this work, we explore the use of fluorescent particle-streak analysis to directly measure the local velocity field of a pressure-driven flow, introducing a new Python package (FSVPy) to perform the analysis. Fluorescent streak velocimetry (FSV) combines high-speed imaging with highly fluorescent particles to produce images that contain fluorescent streaks, whose length and intensity can be related to the local flow velocity. By capturing images throughout the sample volume, the three-dimensional velocity field can be quantified and reconstructed. We demonstrate this technique by characterizing the channel flow profiles of several non-Newtonian fluids: micellar Cetylpyridinium Chloride solution, Carbopol 940, and Polyethylene Glycol. We then explore more complex flows, where significant acceleration is created due to micro-scale features encountered within the flow. We demonstrate the ability of FSVPy to process streaks of various shapes, and use the variable intensity along the streak to extract position-specific velocity measurements from individual images. Thus, we demonstrate that FSVPy is a flexible tool that can be used to extract local velocimetry measurements from a wide variety of fluids and flow conditions.