Effects of electrostatics on granular dynamics

静电对颗粒动力学的影响

• 批准号: 1804286
• 负责人: Troy Shinbrot
• 金额: $ 29.97万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1804286&HistoricalAwards=false
• 关键词: Effects; electrostatics; granular; dynamics

Powders and grains are used by the thousands of tons to process polymers, catalysts, pharmaceuticals, and building materials. However, when powders and grains are electrically charged, they stick to surfaces and collect into aggregates. This leads to severe industrial problems, for example, producing large variations in the active ingredient concentration in pharmaceuticals. Likewise, sticking of thick, tenacious layers of polymers within processing equipment can force manufacturers to shut down operations and jack-hammer the stuck layers from the equipment walls. On the positive side, some technologies such as electrospraying and photocopying rely on the sticking of charged particles. Despite the profound problems and significant opportunities associated with granular charging and sticking, the topic is remarkably poorly understood. In previous work, the principal investigator has shown that particle aggregates are affected by patterns of charge, rather than total charge, on granular surfaces. The research in this award will develop new methods to measure charge patterns that correlate to sticking behaviors. The research team will perform both computer simulations and laboratory tests to confirm the connection between these new measurements and the formation of electrostatic sticking behaviors. New methods to control sticking in industrial operations will also be investigated.The research will consist of three specific aims. First, investigators will develop and validate a method of measuring dipole moments of free particles in microgravity experiments designed to evaluate electrostatic aggregation of free particles in vacuum and under microgravity -- i.e. under nearly ideal conditions. These experiments are being performed by collaborators through separate funding. Second, the experiments produce aggregates of 50 micron particles whose individual charges can be individually evaluated: the principal investigator and his team will use this information as input to simulations of forces acting on the aggregates to establish the magnitudes of net charge and dipole moments on each particle required to hold the aggregates together. The outcome at this point will be direct, computer-guided experimental evaluations of relative strengths of dipole and net charge influences on aggregate cohesion. Third, the researchers will perform independent experiments to evaluate the net charge and dipole moment on individual particles involved in controlled collisions. This will permit them to both establish how large dipole components are likely to become as a result of collisional dynamics, and to determine whether these magnitudes agree with the microgravity experiments. Having completed these aims, the investigators will for the first time have access to experimentally validated methods for obtaining dipole moments of free particles. The researchers will have applied the methods to the description of purely electrostatic forces acting both on aggregates ("aggregation"), and between aggregates and surfaces ("sticking"). This analysis will permit the reliable evaluation of the influence of electrostatics on sticking in a unique set of experiments and simulations.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.

成千上万吨的粉末和谷物被用于加工聚合物、催化剂、药品和建筑材料。然而，当粉末和颗粒带电时，它们会粘在表面上并聚集成聚集体。这导致了严重的工业问题，例如，在药品的有效成分浓度产生很大的变化。同样，如果在加工设备中粘上粘稠、坚韧的聚合物层，制造商可能不得不停止作业，用千斤顶锤将粘稠的聚合物层从设备壁上清除。积极的一面是，一些技术，如电喷涂和复印依赖于带电粒子的粘附。尽管颗粒充电和粘接存在深刻的问题和重大的机遇，但人们对这个话题的理解却非常少。在之前的工作中，首席研究员已经表明，颗粒表面上的颗粒聚集受到电荷模式的影响，而不是总电荷的影响。该奖项的研究将开发新的方法来测量与粘附行为相关的电荷模式。研究小组将进行计算机模拟和实验室测试，以确认这些新测量结果与静电粘附行为形成之间的联系。还将研究控制工业操作中粘滞的新方法。这项研究将包括三个具体目标。首先，研究人员将开发并验证一种在微重力实验中测量自由粒子偶极矩的方法，该方法旨在评估自由粒子在真空和微重力下的静电聚集——即在接近理想的条件下。这些实验由合作者通过单独的资金进行。其次，实验产生50微米粒子的聚集体，其单个电荷可以单独评估：首席研究员和他的团队将使用这些信息作为模拟作用在聚集体上的力的输入，以建立将聚集体聚集在一起所需的每个粒子的净电荷和偶极矩的大小。在这一点上的结果将是直接的，计算机引导的实验评估相对强度的偶极子和净电荷对聚集体凝聚力的影响。第三，研究人员将进行独立实验来评估受控碰撞中单个粒子的净电荷和偶极矩。这将使他们能够确定由于碰撞动力学的结果，偶极子分量可能会变成多大，并确定这些大小是否与微重力实验相符。在完成这些目标后，研究人员将首次获得实验验证的方法来获得自由粒子的偶极矩。研究人员将把这些方法应用于描述作用于聚集体（“聚集”）和聚集体与表面（“粘附”）之间的纯静电力。这种分析将允许在一套独特的实验和模拟中可靠地评估静电对粘着的影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Juggling dynamics

杂耍动态

• DOI: 10.1063/pt.3.4417
• 发表时间: 2020
• 期刊: Physics Today
• 影响因子: 3.5
• 作者: Botvinick-Greenhouse, Jonah;Shinbrot, Troy
• 通讯作者: Shinbrot, Troy

Dynamic pilot wave bound states

动态导频波束缚态

• DOI: 10.1063/1.5116695
• 发表时间: 2019
• 期刊: Chaos: An Interdisciplinary Journal of Nonlinear Science
• 作者: Shinbrot, Troy

Multiple timescale contact charging

多时间尺度接触充电

• DOI: 10.1103/physrevmaterials.2.125003
• 发表时间: 2018
• 期刊: Physical Review Materials
• 影响因子: 3.4
• 作者: Shinbrot, Troy;Ferdowsi, Behrooz;Sundaresan, Sankaran;Araujo, Nuno A. M.
• 通讯作者: Araujo, Nuno A. M.

Electrical charging overcomes the bouncing barrier in planet formation

• DOI: 10.1038/s41567-019-0728-9
• 发表时间: 2020-02-01
• 期刊: NATURE PHYSICS
• 影响因子: 19.6
• 作者: Steinpilz, Tobias;Joeris, Kolja;Wurm, Gerhard
• 通讯作者: Wurm, Gerhard

Charging at a distance

远距离充电

• DOI: 10.1103/physrevmaterials.2.115603
• 发表时间: 2018
• 期刊: Physical Review Materials
• 影响因子: 3.4
• 作者: Shinbrot, Troy;Jones, Brandon;Saba, Pranav
• 通讯作者: Saba, Pranav