Analysis and Rheological Measurements of Suspensions of Magnetic Nanoparticles in Oscillating/Rotating Magnetic Fields

摘要-0457359波多黎各大学-马亚戈分校提出了一项关于流体力学特别是磁性复杂流体响应的综合研究和教育工作。研究任务包括对磁流体、悬浮在粘弹性流体中的永久磁化纳米颗粒、磁流变液和磁流变液复合材料的交流磁场响应进行协调的实验和理论研究。要考虑的具体问题包括圆柱形容器和同轴圆柱体几何形状中的流体由于均匀旋转磁场而产生的流动和扭矩，平板和锥板几何形状沿轴向的DC/AC场，以及平板-平板和圆锥板情况下平板平面内的均匀旋转磁场。对于磁流体，在线性磁化极限下用摄动法求解铁流体动力学方程，在非线性磁化区内用数值方法求解。计划中的实验将使用改装的流变仪和粘度计来测量集装箱壁上的扭矩，并使用超声波多普勒测速仪来测量诱导流场，以检验这些分析的结果。最后，分析了平面Poiseuille/Couette流在振荡/旋转均匀磁场作用下的铁水动力流动稳定性，以及同轴圆柱体Couette几何结构在外加振荡轴向磁场作用下的铁水动力流动稳定性分析，后者作为项目的一部分得到了实验验证。教育工作的重点是用化学工程的最新发展来振兴本科生和研究生的流体力学和传输现象课程，包括拟议的研究成果，现象和非牛顿流体处理的问题和实例，以及利用有限元技术对复杂问题进行建模，从而满足更新我们核心课程的迫切需要。智力优势：拟议的研究旨在填补磁活性复杂流体文献中的空白，在这些文献中，流体对应用交流电场的响应的协调实验和理论研究将对进一步理解和应用开发有价值。要研究的流体从基本的角度来看是很有趣的，因为它们可能维持电磁体耦合，从而导致不对称的应力状态，并需要考虑内部角动量守恒。从实际应用的角度来看，通过所提出的研究所获得的知识将有助于促进这些在交变磁场作用下的磁性活性复杂流体的应用，包括磁性流体热疗和基于磁性纳米颗粒的纳米传感器。用拟议的研究成果更新本科流体力学和研究生运输现象课程的教育努力将满足不断增长的更新核心化学工程课程的需求，以应对未来几代人面临的挑战。广泛影响：在波多黎各大学马亚圭兹分校执行拟议的研究和教育任务，该校区是一个非博士学位授予(根据NSF定义)的拉美裔服务机构，为NSF提供了推进各种更广泛的影响优先领域的特殊机会。UPRM平均每年毕业110名学士学位和10名MS化学工程师，几乎所有人都是拉美裔美国公民，其中68%是女性。我们有很大一部分本科生在UPRM和美国的暑期项目(如NSF REU)中都很活跃。这些学生中的许多人随后进入美国的大学攻读研究生学位。此外，随着最近在智利设立了一个博士课程，UPRM有可能进一步促进拉美裔美国人参与该国的博士水平的研究和教育。为了实现这些目标并更好地为这些学生服务，拟议的教育任务旨在更新核心课程，用与拟议研究和应对后代面临的挑战有关的材料开设新课程。此外，PI将指导进行拟议研究的本科生和研究生。这项拟议的研究旨在分析和测试具有磁性的复杂流体，目的是加深我们对这些系统的了解，并开发下一代仪器来研究它们的行为。最后，拟议的研究和教育任务的结果将通过相关研究和教育文献以及通过国家和国际会议传播

ABSTRACT - 0457359University of Puerto Rico - MayaguezA combined research and education effort in fluid mechanics in general and the response of magneticallyactive complex fluids in particular is proposed. Research tasks consist of coordinated experimental and theoretical studies of the AC magnetic field response of ferrofluids, permanently magnetized nanoparticles suspended in viscoelastic fluids, magnetorheological fluids, and magnetorheological fluid composites. Specific problems to be considered include flows and torques due to uniform rotating magnetic fields applied to the fluid in a cylindrical container and in a coaxial cylinder geometry, DC/AC fields along the axis of plateplate and cone-plate geometries, and uniform rotating fields in the plane of the plate in the plate-plate and cone-plate situations. For ferrofluids, the equations of ferrohydrodynamics will be solved using perturbation methods in the linear magnetization limit and using numerical methods in the nonlinear magnetization regime. Planned experiments will test the results of these analyses using modified rheometers and viscosimeters to measure the torques on container walls and using Ultrasonic Doppler Velocimetry to measure the induced flow fields. Finally, analyses of ferrohydrodynamic flow stability for the planar Poiseuille/Couette flow in the presence of oscillating/rotating uniform magnetic field and for the coaxial cylinder Couette geometry with applied oscillating axial field are proposed, with the latter being verified experimentally as part of the project. Educational efforts are focused on invigorating undergraduate and graduate courses on fluid mechanics and transport phenomena with recent developments in Chemical Engineering, including results from the proposed research, and problems and examples of phenomena and processing of non-Newtonian fluids, and utilization of finite element techniques to model complex problems, thereby addressing the pressing need to update our core curriculum.Intellectual Merit: The proposed research aims to fill gaps in the magnetically-active complex fluids literature where coordinated experimental and theoretical studies of fluid response to applied AC fields would be of value to further understanding and application development. The fluids to be studied are interesting from a fundamental perspective as they may sustain electromagnetic body couples, consequently resulting in asymmetric states of stress and the need to consider internal angular momentum conservation. From a practical perspective, the knowledge gained through the proposed research will serve to advance applications of these magnetically active complex fluids subjected to applied AC fields, including magnetic fluid hyperthermia and magnetic nanoparticle based nanosensors. Educational efforts to renovate the undergraduate fluid mechanics and graduate transport phenomena courses with results from the proposed research will satisfy the growing need to renovate the core Chemical Engineering curriculum to address the challenges to be faced by future generations.Broader Impact: Performing the proposed research and education tasks at the University of Puerto Rico Mayaguez campus, a non-PhD granting (as per NSF definitions) Hispanic Serving Institution, provides special opportunities to advance various broader impact priority areas for NSF. The UPRM graduates an average of 110 BS and 10 MS Chemical Engineers each year, practically all of which are Hispanic US citizens and 68% of which are female. A significant fraction of our undergraduate students are active in research both at UPRM and in summer programs (such as NSF REU) in the US. Many of these students subsequently attend Universities in the US to pursue graduate degrees. Furthermore, with the recent establishment of a doctoral program in ChE, the UPRM has the potential of further advancing the participation of Hispanics in doctoral-level research and education in the Nation. To achieve these goals and to better serve these students, the proposed education tasks aim to renovate core curricula and create new courses with material related to the proposed research and addressing challenges to be faced by future generations. In addition, the PI will mentor undergraduate and graduate students performing the proposed research. The proposed research aims to analyze and test magnetically active complex fluids with the objective of furthering our understanding of these systems as well as developing next-generation instrumentation to study their behavior. Finally, the results of the research and educational tasks proposed will be disseminated through the relevant research and educational literature, as well as through National and International meetings