The Structure and Dynamics of Thin Film Liquid-Vapor Systems in Microgeometries

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CBET-0854148Breuer A three year program will be conducted to study the structure and dynamics of evaporation in micron-scale systems. We plan to explore the manner in which liquid-vapor systems behave in confined geometries with typical scales of 0.1 - 20 microns where the role of the transitional zone between the bulk meniscus and the adsorbed liquid film becomes dominant. Of particular interest will be the description of the role of the thin liquid transition film that leads the bulk liquid phase and has been demonstrated to contribute significantly to the overall heat and mass transfer in small systems. The effects of fluid and surface chemistry, geometry, and the presence of fluid additives will be systematically explored. Novel experimental techniques will be used to measure velocities and temperatures in the 200 nm near the liquid-solid interface, as well as to directly measure the thickness of the thin liquid film on the solid substrate as it evolves. Measurements of fluid velocities and evaporation rates will be taken and compared with theoretical and numerical predictions for similar systems.Intellectual Merit: The behavior of two-phase systems in microgeometries, and in particular, the character of the thin liquid film on a smooth surface continues to be a problem of critical importance and one in which there is active debate in the heat transfer and fluid mechanics literature. As microengineering continues to push towards smaller scales, the characterization and modeling of the physics of these thermal transport problems becomes more relevant and challenging. High-quality experimental data are critical in providing guidance to models and numerical experiments in this field. Broader Impacts: The results obtained during this research will help guide design and analysis for a wealth of micron-scale heat transfer systems (heat pipes, capillary pumped loops, etc.) that can be used in a multitude of applications such as chip cooling, thermal control in micro-systems, space power applications, etc. The project will support the training of one graduate student to work closely with the PI. The project will also involve an undergraduate student. We will also continue to build on our successful history of recruiting under-represented groups (through the Leadership Alliance), and will leverage and participate with the Brown University MRSEC outreach program, for example by working with the K-12 Teacher Training Program and high school student Research Experience Program. Lastly, we will continue to work with media producers (such as NOVA and Discovery Channel) in the development of science programming for a wide audience.