Turbulent flows that contain particles occur in a variety of industrial, biological, and environmental processes. The analysis of these flows is challenging, because interactions between the suspended particles and the surrounding fluid not only affect dynamics of the particles, but also influence characteristics of the overall flow. This award will support development of computational and experimental tools to better understand how particle-fluid interactions at the particle scale influence transport in turbulent flow at large scales. An imaging system will be constructed to record three-dimensional velocity fields of particle-laden fluids in turbulent open-channel flow. Experimental results will be compared with numerical simulations of the identical flow to validate the simulation methods and provide additional insight into relationships between particle dynamics and flow. The research team will incorporate results from the project in a new short course that will combine computational fluid dynamics with new techniques in computational imaging and computer vision. An instructional module illustrating these methods will be developed for high school students and teachers participating in the High School Summer Research program at the University of Delaware.
A plenoptic particle tracking velocimetry system will be constructed that can measure the three-component velocity fields in three-dimensional, turbulent, particle-laden flows at both micro- and macro-scales. This velocimetry method uses a plenoptic camera that can record many images of a collection of particles from different viewpoints and angles at the same time. Then, computer vision algorithms are applied to recover accurately the instantaneous positions of the particles in three dimensions, which can be used to find the velocity fields. In addition, the particle tracking system in this project will be designed to capture the rotational velocity of individual particles. In parallel, a highly scalable particle-resolved simulation tool based on the mesoscopic lattice Boltzmann approach will be applied to resolve the three-dimensional motion at all scales. Results from the simulations will be compared with experimental data at all scales. At the particle scale, these data include trajectories, velocities, accelerations, and angular velocities of particles, particle-wall and particle-free surface interactions, as well as local flow statistics near the surface of a solid particle. At the system scale, the tools will be used to study turbulence modulation, flow drag, and flow transition in the presence of the finite-size solid particles.
