Collaborative Research: Electrorotational fluid instabilities

合作研究：电旋转流体不稳定性

• 批准号: 1704996
• 负责人: Petia Vlahovska
• 金额: $ 25.39万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1704996&HistoricalAwards=false
• 关键词: Collaborative; Research; Electrorotational; fluid; instabilities

A particle can spontaneously start spinning in an electric field, a phenomenon called Quincke rotation. This project will explore fundamentals and applications of electrorotation in fluid systems such as liquid droplets. The fluid-fluid interface can flow and the drop can deform, which creates a plethora of unexplained flow behaviors: a drop can tumble or beat like a heart, or small particles attached to the drop surface can cluster into vortices. The project will experimentally map electrorotational flows as a function of fluid properties and field strength. The experimental results will be used to develop models to elucidate the observed instabilities. In addition to advancing basic knowledge, the research will provide insights on how to harness these novel electrorotational flows for engineering of complex flows or of novel colloidal products such as patchy particles with dynamic surface patterns. At UCSD, the PI has been involved in engineering outreach to local high-school students, in the form of a summer course entitled "Introduction to Fluid Mechanics in Engineering: From a Straw to an Airplane." The results from this research can be folded into materials to support outreach of students.The electrohydrodynamic flow about a leaky-dielectric liquid drop can undergo intriguing instabilities which involve generation of rotational flow, e.g., drop steady tilt or tumbling, or of vortices as previously observed on the surface of particle-coated drops. This project will establish the mechanisms of these electorotational fluid instabilities by developing (i) numerical simulations, based on the three-dimensional Boundary Integral Method, and (ii) analytical models using asymptotic methods, of drop dynamics in electric fields. Experiments will be designed and carried out to guide and validate the computations and analytical results. The driving hypothesis is that electrorotational fluid instabilities are related to the Quincke effect (the spontaneous rotation of a particle in a uniform DC electric field occurring above a threshold field strength). The research outcomes will lead to a much deeper understanding of the underlying physics as well as the discovery of new dynamical regimes and engineering opportunities. The potentially transformative nature of the proposal lies in the unexplained emergent behavior of the system that could inspire new research directions and applications related to complex fluids, instabilities and interfacial flows.

粒子可以在电场中自发地开始旋转，这种现象称为昆克旋转。该项目将探索电旋转在流体系统（例如液滴）中的基础知识和应用。流体-流体界面可以流动，液滴可以变形，从而产生大量无法解释的流动行为：液滴可以像心脏一样翻滚或跳动，或者附着在液滴表面的小颗粒可以聚集成漩涡。该项目将通过实验将电旋转流绘制为流体特性和场强的函数。实验结果将用于开发模型来阐明观察到的不稳定性。除了推进基础知识之外，该研究还将提供有关如何利用这些新颖的电旋转流来设计复杂流或新颖的胶体产品（例如具有动态表面图案的斑片颗粒）的见解。在加州大学圣地亚哥分校，PI 一直以暑期课程的形式参与到当地高中生的工程推广活动，题为“工程流体力学导论：从吸管到飞机”。这项研究的结果可以折叠成材料来支持学生的推广。漏电液滴的电流体动力学流动可能会经历有趣的不稳定性，其中涉及旋转流的产生，例如液滴稳定倾斜或翻滚，或如前所述的涡流在颗粒涂覆的液滴表面观察到。该项目将通过开发（i）基于三维边界积分法的数值模拟和（ii）使用渐近方法的电场中液滴动力学分析模型来建立这些旋转流体不稳定性的机制。将设计和进行实验来指导和验证计算和分析结果。驱动假设是电旋转流体的不稳定性与昆克效应（粒子在均匀直流电场中发生高于阈值场强的自发旋转）有关。 研究成果将导致对基础物理学的更深入理解以及新的动力学机制和工程机会的发现。该提案的潜在变革性在于系统无法解释的突发行为，可以激发与复杂流体、不稳定性和界面流相关的新研究方向和应用。

项目成果

Quincke rotor dynamics in confinement: rolling and hovering

• DOI: 10.1039/c9sm01163c
• 发表时间: 2019-08-28
• 期刊: SOFT MATTER
• 影响因子: 3.4
• 作者: Pradillo, Gerardo E.;Karani, Hamid;Vlahovska, Petia M.
• 通讯作者: Vlahovska, Petia M.

Tuning the Random Walk of Active Colloids: From Individual Run-and-Tumble to Dynamic Clustering

• DOI: 10.1103/physrevlett.123.208002
• 发表时间: 2019-11-14
• 期刊: PHYSICAL REVIEW LETTERS
• 影响因子: 8.6
• 作者: Karani, Hamid;Pradillo, Gerardo E.;Vlahovska, Petia M.
• 通讯作者: Vlahovska, Petia M.

Emergence of lanes and turbulent-like motion in active spinner fluid

• DOI: 10.1038/s42005-021-00596-2
• 发表时间: 2021-05-10
• 期刊: COMMUNICATIONS PHYSICS
• 影响因子: 5.5
• 作者: Reeves, Cody J.;Aranson, Igor S.;Vlahovska, Petia M.
• 通讯作者: Vlahovska, Petia M.

Dielectric Spherical Particle on an Interface in an Applied Electric Field

施加电场中界面上的介电球形颗粒

• DOI: 10.1137/18m1195668
• 发表时间: 2019
• 期刊: SIAM Journal on Applied Mathematics
• 影响因子: 1.9
• 作者: Hu, Yi;Vlahovska, Petia M.;Miksis, Michael J.
• 通讯作者: Miksis, Michael J.

Numerical and asymptotic analysis of the three-dimensional electrohydrodynamic interactions of drop pairs

• DOI: 10.1017/jfm.2020.1007
• 发表时间: 2020-04
• 期刊: Journal of Fluid Mechanics
• 影响因子: 3.7
• 作者: Chiara Sorgentone;Jeremy I. Kach;Aditya S. Khair;L. Walker;Petia M. Vlahovska