Experimental Flow Visualization Around a Sphere Using Lagrangian Particle Tracking

Abstract The wake behind a sphere is characterized by complex, highly three-dimensional fluid phenomena, including flow separation, recirculation, and unsteady vortex shedding [1]. Capturing these highly dynamic flow states in a single field of view requires advanced volumetric measurement techniques. Shake-the-Box (STB), a Lagrangian Particle Tracking (LPT) method, achieves this by measuring the 3D positions, temporal trajectories, and velocities of individual Helium-Filled Soap Bubbles (HFSB). Consequently, the instantaneous volumetric wake of the sphere can be captured with high temporal and spatial resolution, enabling the direct analysis of complex flow topologies.