A 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
