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41439-AC9
Stability and Dynamics of Fluid Flow Near Polymer Gels
We are conducting fundamental research on problems involving the stability and dynamics of fluid flow near polymer gels, a topic directly related to petroleum because of the use of gel-like materials that come into contact with flowing fluids during oil recovery processes. Fundamental understanding gleaned from these studies will not only be relevant to the petroleum field, but also to fields where the interaction between flowing fluids and deformable solids is potentially important, such as microfluidics, coating and printing processes, separations, and polymer processing. During the past year, we focused on the following activities:
-Collaboration with Prof. Edward L. Cussler of the University of Minnesota to exploit fluid-gel interfacial instabilities to improve mass transfer in microchannels, which is an important concern in microfluidics and separations processes. We demonstrated experimentally that these instabilities can improve mass transfer coefficients by 25%. Ours are the first experimental observations to establish transport enhancement by fluid-gel interfacial instabilities. We also developed, and validated experimentally, a simple model describing how rigid spacers can be designed to improve mass transfer. In some cases, we observed improvements in the mass transfer coefficient of up to 400%, which is considerably larger than what has been seen by others. Two papers on this work are currently being prepared for publication.
-Collaboration with Dr. Erik K. Hobbie of the National Institute of Standards and Technology to visualize and rheologically characterize fluid-gel interfacial instabilities. We have observed a number of intriguing nonlinear phenomena and used these, along with simple models, to extract information about the rheological properties of the gel. This is a potentially powerful method for characterizing soft materials that are not well-suited for standard rheological instruments. A paper on this work has been submitted.
-Collaboration with Prof. Omar K. Matar of Imperial College examining how the dynamics and stability of a thin liquid film flowing down a flexible inclined wall are affected by the wall properties. We have delineated how various wall and liquid properties can influence film behavior. This work has yielded fundamental insight that we expect will be useful in understanding flow phenomena near polymer gels and in designing gels (and other types of deformable solids) to respond to flows in a desired way. One paper on this work has been published, and another has been submitted.
-Collaboration with Prof. Mihailo Jovanović of the University of Minnesota to apply newly developed methods for analyzing the stability of fluid flows to the problem of fluid-gel interfacial instabilities. These new methods can provide considerably more information than traditional linear stability analysis. As a starting point, we are considering fluid phases alone before moving to the considerably more difficult problem of fluid-gel interfaces. Our results indicate that three-dimensional disturbances may be more important than has previously been recognized. Such disturbances may also account for some of our experimental observations (see above). In a related effort, we are developing boundary integral methods that we eventually plan to use to explore nonlinear aspects of fluid-gel interfacial instabilities.
Receipt of this grant is significant because it enables the full-time support of a PhD student. As a result, seven papers have been published since the grant was awarded. The education of students is also markedly enhanced because the grant enables travel to professional meetings, where students gain experience in making presentations and get exposed to a broad variety of research activities.
