Lagrangian Measurements and Large Eddy Simulation of Inertial Particles in Turbulent Flows with and without Large-Scale Anisotropy

具有和不具有大尺度各向异性的湍流中惯性粒子的拉格朗日测量和大涡模拟

• 批准号: 0756510
• 负责人: Lance Collins
• 金额: $ 37.5万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-15 至 2012-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0756510&HistoricalAwards=false
• 关键词: Lagrangian; Measurements; Large; Eddy; Simulation

CBET-0756510CollinsThe PIs plan to develop a large-eddy simulation (LES) subgrid closure for the motion of inertial particles in high-Reynolds-number turbulence that captures the mean concentration and fluctuations that arise due to inertial particle clustering. To assess the model, the PIs will exploit state-of-the-art particle tracking capabilities developed under a recent NSF Major Research Instrumentation (MRI) grant to study the dynamics of inertial particle pairs inside a von Karman swirl flow chamber. The PIs will perform fully-resolved direct numerical simulations (DNS) of isotropic, particle-laden turbulence and compare those results to the LES model. A second set of Lagrangian measurements will be focused on the impact of large-scale anisotropy and inhomogeneities on the motion of particles. These measurements will be carried out in a high- Reynolds-number wind tunnel facility developed under the MRI grant. The PIs will modify the earlier experiments in two ways. First, homogeneous turbulent shear flow (HTSF) and a turbulent boundary layer (TBL) will be studied by introducing a shear generator or a flat plate into the test section of the wind tunnel. Second, two additional cameras will be incorporated into the optical setup, enabling 3D particle trajectories to be measured allowing study of the effect of large-scale anisotropy on the motion of particles. Aside from the fundamental information these measurements will provide, the PIs will test the LES in increasingly complex (realistic) flows to discover what elements of the model would need further development to accommodate large-scale anisotropy. DNS of HTSF with particles will be performed using a newly developed spectral code, and Lagrangian particle statistics will be measured. DNS will support testing of the LES subgrid closure in limits of the parameter space that cannot be reached by the experiment. In addition, data from the DNS test the particle tracking codes used in the experiment. The planned Lagrangian measurements and DNS will uncover the effect mean velocity gradients and walls have on the motion of particles, providing an important testbed for the LES model, as well as new knowledge to be made available to the community via publications and a public web site. The PIs have been heavily involved with outreach throughout their careers. Recent activities include middle school and high school activities for girls, recruiting and mentoring of minority graduate students through the Sloan Fellowship program and the NSF AGEP award the PIs share, and outreach within the community on the environment. The PIs also recently created the International Collaboration on Turbulence Research (ICTR) to facilitate interactions with other members of our community throughout the world.

CBET-0756510CollinsPIS计划开发大涡模拟(LES)子网格闭合，用于高雷诺数湍流中惯性粒子的运动，捕捉由于惯性粒子聚集而产生的平均浓度和波动。为了评估该模型，PI将利用最近美国国家科学基金会重大研究仪器(MRI)拨款开发的最先进的粒子跟踪能力来研究冯·卡曼旋流室内惯性粒子对的动力学。PI将对各向同性、含颗粒的湍流进行全分辨直接数值模拟，并将结果与大涡模拟结果进行比较。第二组拉格朗日测量将集中在大尺度各向异性和不均匀对粒子运动的影响上。这些测量将在核磁共振赠款下开发的高雷诺数风洞设施中进行。PI将以两种方式修改先前的实验。首先，通过在风洞试验段引入剪切发生器或平板来研究均匀湍流剪切流(HTSF)和湍流边界层(TBL)。其次，两个额外的摄像头将被整合到光学装置中，从而能够测量3D粒子轨迹，从而能够研究大规模各向异性对粒子运动的影响。除了这些测量将提供的基本信息外，PI还将在日益复杂(现实)的流动中测试LES，以发现模型的哪些元素需要进一步开发以适应大规模的各向异性。将使用新开发的光谱代码执行HTSF与粒子的解析，并将测量拉格朗日粒子统计。域名系统将支持在实验无法达到的参数空间限制内测试LES子网格闭合。此外，来自域名系统的数据测试了实验中使用的粒子跟踪代码。计划中的拉格朗日测量和域名系统将揭示平均速度梯度和墙对粒子运动的影响，为大涡模拟提供一个重要的试验台，并通过出版物和公共网站向社区提供新的知识。PI在他们的职业生涯中一直积极参与外展活动。最近的活动包括针对女孩的初中和高中活动，通过斯隆奖学金计划和国家科学基金会AGEP奖招募和指导少数族裔研究生，以及在社区内就环境进行宣传。国际警察组织最近还建立了湍流研究国际合作(卢旺达问题国际法庭)，以促进与世界各地社区其他成员的互动。