Regimes of particle settling for finite-sized particles in the inertial range of turbulence

湍流惯性范围内有限尺寸颗粒的颗粒沉降规律

基本信息

批准号：
2211704
负责人：
Nimish Pujara
金额：
$ 31.01万
依托单位：
University of Wisconsin-Madison
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：
2022-04-01 至 2025-03-31
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2211704&HistoricalAwards=false
关键词：
Regimes particle settling finite sized

项目摘要

Particle settling is affected by turbulence in various environmental and industrial settings. Examples include vertical fluxes of nutrients via the settling of plankton and marine snow particles, deposition of marine debris such as microplastics on river, lake and sea beds, and settling tanks in wastewater treatment facilities. An accurate understanding of settling velocities in such applications would improve efficiency and minimize environmental impacts, but gaining this understanding is challenging since such particles are often too large to be modelled as small points. Thus, the principal aim of this project is to understand the underlying physics that leads to altered settling rates of larger particles in turbulent flows. The project will also include the design of a bench-top experimental facility that will provide research, education, and outreach opportunities for undergraduate students in the Civil and Environmental Engineering department at UW-Madison. Settling of finite-sized particles in turbulence are characterized by (1) particle interactions with turbulent flow that occur at Reynolds numbers above unity and (2) complex and multiscale particle-turbulence interactions as the particles distort the local flow around them. Previous work in this regime has found that particle settling rates in turbulence are reduced relative to terminal velocities in quiescent fluid, but it is unclear how this should be understood in terms of the underlying physical mechanisms. This project seeks to fill this gap in understanding by conducting a thorough experimental investigation into settling regimes of finite-sized particles, exploring a range of particle sizes, densities, and volume fractions. The experiments will use the newly constructed octagonal turbulence chamber and three-dimensional high-speed camera measurements of flow and particle motion. The focus will be on identifying new scaling parameters that capture turbulence effects on particle settling rates, including the effects of particle clustering. It is expected that this approach will lead to the identification of mechanisms that alter particle settling rates based on scaling laws that collapse data across a range of parameters. In turn, this understanding will lead to a new predictive model that could inform future designs in water treatment and ecosystem engineering.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.

粒子沉降受到各种环境和工业环境中的湍流的影响。例子包括通过浮游生物和海洋雪地颗粒的沉降，海洋碎屑的沉积，例如河流，湖泊和海床上的微型塑料，以及废水处理设施中的沉降罐。对此类应用中的沉降速度的准确理解将提高效率并最大程度地减少环境影响，但是获得这种理解是具有挑战性的，因为这种颗粒通常太大而无法建模为小点。因此，该项目的主要目的是了解导致湍流中较大颗粒的沉降速率改变的基本物理。该项目还将包括一个台式实验设施的设计，该设施将为UW-Madison的民用和环境工程系的本科生提供研究，教育和外展机会。湍流中有限大小的颗粒的沉降的特征是（1）粒子与统一以上的雷诺数数量发生的湍流相互作用，并且（2）粒子会扭曲周围的局部流动，并（2）复合和多尺度粒子扰动相互作用。该制度的先前工作发现，相对于静态液中的末端速度，湍流中的粒子沉降速率降低了，但是目前尚不清楚如何通过基本的物理机制理解这一点。该项目旨在通过对有限大小颗粒的定居方式进行彻底的实验研究，探索一系列粒径，密度和体积分数，以填补这一空白。实验将使用新建的八角形湍流室和流动和粒子运动的三维高速摄像头测量。重点将放在确定新的缩放参数上，以捕获湍流对粒子沉降速率的影响，包括粒子聚类的影响。预计这种方法将导致基于缩放定律改变粒子沉降速率的机制，从而改变粒子沉降速率，从而使数据崩溃了一系列参数。反过来，这种理解将导致一种新的预测模型，该模型可以为水处理和生态系统工程的未来设计提供信息。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛的影响评估的评估来获得支持的。

项目成果

期刊论文数量（4）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Wave-averaged motion of small particles in surface gravity waves: Effect of particle shape on orientation, drift, and dispersion

表面重力波中小颗粒的波平均运动：颗粒形状对方向、漂移和色散的影响

DOI：
10.1103/physrevfluids.8.074801
发表时间：
2023
期刊：
Physical Review Fluids
影响因子：
2.7
作者：
Pujara, Nimish;Thiffeault, Jean-Luc
通讯作者：
Thiffeault, Jean-Luc

Homogeneous turbulence in a random-jet-stirred tank

随机喷射搅拌槽中的均匀湍流

DOI：
10.1007/s00348-023-03721-9
发表时间：
2023
期刊：
Experiments in Fluids
影响因子：
2.4
作者：
Bang, Joo Young;Pujara, Nimish
通讯作者：
Pujara, Nimish

Multisensory navigational strategies of hatchling fish for dispersal

DOI：
10.1016/j.cub.2023.09.070
发表时间：
2023-11-20
期刊：
CURRENT BIOLOGY
影响因子：
9.2
作者：
Lin，Allia;Alvarez-Salvado，Efren;Ehrlich，David E.
通讯作者：
Ehrlich，David E.

Microswimmer trapping in surface waves with shear

DOI：
10.1098/rspa.2023.0280
发表时间：
2023-10-11
期刊：
PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
影响因子：
3.5
作者：
Ventrella，F. M.;Pujara，N.;De Lillo，F.
通讯作者：
De Lillo，F.