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

摘要-0457359波多黎各大学-马亚圭兹提出了流体力学和磁活性复杂流体响应的综合研究和教育努力。研究任务包括铁磁流体、悬浮在粘弹性流体中的永磁纳米颗粒、磁流变流体和磁流变流体复合材料的交流磁场响应的协调实验和理论研究。 要考虑的具体问题包括由于均匀旋转磁场施加到圆柱形容器和同轴圆柱几何形状中的流体而产生的流动和扭矩，沿板-板和锥-板几何形状的轴线沿着的DC/AC场，以及在板-板和锥-板情况下板平面内的均匀旋转场。对于铁磁流体，铁磁流体动力学方程将使用微扰方法在线性磁化极限和使用数值方法在非线性磁化制度。 计划的实验将测试这些分析的结果，使用改进的流变仪和粘度计测量容器壁上的扭矩，并使用超声多普勒测速仪测量诱导流场。最后，铁流体动力学流动的稳定性分析的平面Poilluille/Couette流中存在的振荡/旋转均匀磁场和同轴圆柱Couette几何形状与施加的振荡轴向场的建议，后者被实验验证的项目的一部分。教育工作的重点是振兴本科和研究生课程的流体力学和运输现象与化学工程的最新发展，包括从拟议的研究结果，和问题和例子的现象和处理的非牛顿流体，并利用有限元技术来模拟复杂的问题，从而解决迫切需要更新我们的核心课程。智力优点：拟议的研究旨在填补空白的磁活性复杂流体文献中，协调的实验和理论研究的流体响应应用AC字段将有价值的进一步理解和应用开发。要研究的流体是有趣的，从一个基本的角度来看，因为它们可能会维持电磁体耦合，从而导致不对称的应力状态，需要考虑内部角动量守恒。 从实践的角度来看，通过拟议的研究所获得的知识将有助于推进这些磁活性复杂流体的应用，包括磁流体热疗和基于磁性纳米颗粒的纳米传感器。教育工作，以更新本科流体力学和研究生运输现象课程的结果，从拟议的研究将满足日益增长的需要，以更新核心化学工程课程，以应对未来几代人面临的挑战。在波多黎各马亚圭斯大学校园执行拟议的研究和教育任务，一个非博士授予（根据NSF的定义）西班牙裔服务机构，提供特殊的机会，以推进各种更广泛的影响NSF的优先领域。UPRM每年平均有110名BS和10名MS化学工程师毕业，几乎所有这些都是西班牙裔美国公民，其中68%是女性。我们的本科生中有很大一部分都活跃在UPRM和美国暑期课程（如NSF REU）的研究中。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ChE博士课程的建立，UPRM有可能进一步推动西班牙裔美国人参与全国博士级研究和教育。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，并利用与拟议研究有关的材料开设新课程，以应对子孙后代将面临的挑战。此外，PI将指导本科生和研究生进行拟议的研究。拟议的研究旨在分析和测试磁活性复杂流体，目的是加深我们对这些系统的理解，并开发下一代仪器来研究它们的行为。最后，将通过相关的研究和教育文献以及国家和国际会议传播所建议的研究和教育任务的成果

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