Experimental investigation of particle-wake interactions based on settling of finite-size particles

Research on free-falling particles has primarily focused on the role of wake dynamics and vortex shedding of individual particles to characterize their shape-dependent trajectories, the effect of density ratio, and Reynolds number (based on the particle length scale and velocity). When these particles fall in bulk, the wakes of surrounding particles alter the flow fields, which can result in one particle being captured in the wake of another. To further understand this phenomenon, we conducted volumetric experiments to investigate how the particle settling dynamics are affected by the wake of other settling particles. Particles of various shapes (spheres, cylinders, and cuboids) and sizes (6 -12 mm) were first individually released into quiescent water. Then, the particles were released into the bulk wake of both mono- and polydispersed particles. Using four high-speed cameras and multiple LEDs, we captured both 3D particle and fluid motions simultaneously within an imaging domain measuring 90 mm x 90 mm x 40 mm. The images were preprocessed to separate the fluid and particle phases before tracking them using Davis 10.2 Shake-The-Box and Iterative Particle Reconstruction algorithms, respectively. The results, which include the reconstructed dynamics of particles and wakes, will be presented in the meeting.