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

CBET -1510154 PI：Longmire，Ellen包含离散颗粒的湍流发生在许多与气候预测，能源生产和环境保护相关的环境和工业过程中。在环境流动中，颗粒可能是自然的（浮游生物、孢子、沉积物或灰尘）或污染物（塑料、废气或沉降物）。由于流体中的湍流尺度范围很广，以及在颗粒直径尺度上发生的复杂物理相互作用，这些流动很难理解和预测。拟议研究的目标是提高实验和数值模拟能力，以解决固体表面附近湍流中的颗粒/湍流，颗粒/颗粒和颗粒/壁的相互作用，这些相互作用通常决定颗粒沉积和再悬浮速率，混合，补充实验和直接数值模拟将调查颗粒释放到液体湍流边界层流动中的控制，时尚.在颗粒直径超过最小湍流尺度且颗粒雷诺数显著的情况下，将考虑单个移动颗粒和成对碰撞颗粒。实验将采用三维跟踪离散粒子结合时间分辨断层粒子成像测速量化平移和旋转，滑移速度，空间速度梯度所经历的个人和碰撞粒子。发展了一种新的非结构网格的守恒重叠网格方法，并将其应用于模拟和完全解决与实验条件相匹配的湍流流动和运动颗粒上的应力。结果将被应用于评估现有的粒子/力耦合模型，并提出模型改进。该项目将涉及研究生和本科生研究人员。 该项目团队将与当地一所小学的教师和学生合作，激发他们对科学和工程的兴趣，并开发可以纳入所需科学课程的物理和工程活动。

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.