Disentangling Inertial Particle-Turbulence Mechanisms in the Absence of Gravity

解开无重力情况下的惯性粒子湍流机制

• 批准号: 2223235
• 负责人: Raul Cal
• 金额: $ 39.6万
• 依托单位: Portland State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2223235&HistoricalAwards=false
• 关键词: Disentangling; Inertial; Particle; Turbulence; Mechanisms

Volcanic ash transport, atmospheric pollutants, and dust storms on planet Mars are few examples of turbulent flows (i.e., flows with high velocity) laden with particles. Because of its importance and ubiquitousness, turbulent transport of particles has been widely investigated. However, numerous questions remain which limit a comprehensive understanding of this phenomenon and modeling capacities. For instance, it is still unclear whether small spherical particles in a turbulent environment settle slower, faster, or at the same speed than in a quiescent (no flow) fluid. Development of predictive models relies on generating refined experimental and numerical data to accurately characterize the subtle multi-scale physical mechanisms at play. This award aims at exploring particle-turbulence interactions in low-gravity conditions with the goal of separating gravitational and inertial forces to better understand and implement their influence in inertial particle models. Broader impacts are tailored to the participating students and researchers as well as the broader public.Utilizing the Dryden Drop Tower, a unique facility located at PSU, this award will perform a systematic experimental exploration of the single and collective particle interactions with turbulence in microgravity conditions. Microgravity experiments will provide the opportunity to explore the effects purely attributable to inertia. These will be systematically surveyed by considering particles with various response times (tunable by change in material and/or particle size). The objectives of the proposed investigation include: 1) dissociating the effects of particle inertia and gravity on particle-turbulence interactions for both finite-size and punctual single particles, 2) evaluating joint effects promoted by clustering and/or particle-particle interactions of finite size and point-particles in a turbulent flow under microgravity, and 3) developing Lagrangian stochastic models for finite size particles in gravity. Broader impact activities include STEM training at the post-graduate, graduate, and undergraduate level and international research visits. The Oregon Museum of Science and Industry science communication training program will provide a great opportunity for graduate student and post-doctoral researcher to effectively communicate their science with the broader public.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

火星上的火山灰运输、大气污染物和沙尘暴是湍流的几个例子（即，高速流动）中充满颗粒。由于其重要性和普遍性，颗粒的湍流输运已经得到了广泛的研究。然而，仍然存在许多问题，限制了对这一现象的全面理解和建模能力。例如，仍然不清楚湍流环境中的小球形颗粒是否比静止（无流动）流体中的沉降更慢，更快或以相同的速度沉降。预测模型的开发依赖于生成精细的实验和数值数据，以准确表征起作用的微妙的多尺度物理机制。该奖项旨在探索低重力条件下的粒子-湍流相互作用，目的是分离重力和惯性力，以更好地理解和实施它们在惯性粒子模型中的影响。更广泛的影响是针对参与的学生和研究人员以及更广泛的公众。利用德莱登落塔，一个独特的设施位于PSU，这个奖项将进行系统的实验探索的单个和集体粒子与湍流在微重力条件下的相互作用。微重力实验将为探索纯粹由惯性造成的影响提供机会。这些将通过考虑具有不同响应时间的颗粒（通过材料和/或颗粒尺寸的变化可调）进行系统调查。研究的目标包括：1）分离颗粒惯性和重力对颗粒-湍流相互作用的影响，对于有限尺寸和点状的单个颗粒，2）评估微重力下湍流流动中有限尺寸和点颗粒的聚集和/或颗粒-颗粒相互作用所促进的联合效应，和3）开发重力下有限尺寸颗粒的拉格朗日随机模型。更广泛的影响活动包括研究生、研究生和本科生级别的STEM培训以及国际研究访问。俄勒冈州科学与工业博物馆的科学传播培训计划将为研究生和博士后研究人员提供一个很好的机会，使他们能够有效地与更广泛的公众进行科学传播。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。