Tracing of shallow water flows through buoyant fluorescent particles

In this paper, we investigate the feasibility of tracing shallow water flows in illuminated conditions by using buoyant fluorescent particles. We develop an image analysis-based procedure for automatic detection and real-time tracking of particles based on a computationally inexpensive algorithm implemented on recorded videos. The methodology is validated through experiments conducted in a custom-built reclinable miniature channel that is specifically developed for simulating shallow water conditions. The effect of the fluorescent particles' dimensions on their ability to trace water flows is theoretically assessed through a parametric study in which the particle response to different flow velocities is estimated through the Basset-Boussinesq-Oseen equation. Particle velocities extracted through image analysis are compared to particle image velocimetry measurements for selected combinations of slopes and water depths. Experimental results support the potential integration of this methodology in field measurement systems for hillslope overland flow velocity.