UNS: Resolving the Dynamics of Particles in Turbulent Wall-Bounded Flow: DNS and Experiments

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CBET - 1510154PI: Longmire, EllenTurbulent flows containing discrete particles occur in many environmental and industrial processes related to climate prediction, energy production, and environmental conservation. In environmental flows, particles may be natural (plankton, spores, sediment, or dust) or pollutants (plastics, exhaust or fallout precipitates). These flows are difficult to understand and predict due to the wide range of turbulence scales in the fluid as well as the complex physical interactions that occur on the scale of the particle diameter. The goal of the proposed research is to advance experimental and numerical simulation capabilities to resolve particle/turbulence, particle/particle, and particle/wall interactions in turbulent flows near solid surfaces where these interactions often determine particle deposition and resuspension rates, mixing, and transport.Complementary experiments and direct numerical simulations will investigate particles released into liquid turbulent boundary layer flows in a controlled fashion. Single moving particles and pairs of colliding particles will be considered where the particle diameter exceeds the smallest turbulence scales and where the particle Reynolds number is significant. Experiments will employ three-dimensional tracking of discrete particles combined with time-resolved tomographic particle imaging velocimetry to quantify translation and rotation, slip velocities, and spatial velocity gradients experienced by individual and colliding particles. A novel conservative overset grid method for unstructured grids will be developed and applied to simulate and fully resolve flow and stresses on moving particles in turbulent flow matching the experimental conditions. The results will be applied to assess existing particle/force coupling models and to suggest model improvements. The project will involve graduate and undergraduate researchers. The project team will work with teachers and students at a local elementary school to spark interest in science and engineering and to develop hands on physics and engineering activities that can be incorporated into the required science curriculum.