NIRT: Multi-Scale Modeling and Simulation of Adhesion, Nanotribology and Nanofluidics

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0103408RobbinsThis proposal was submitted in response to the solicitation "Nanoscale Science and Engineering" (NSF 00-119).This Nanoscale Interdisciplinary Research Team brings together investigators from a research university (Johns Hopkins), the Naval Academy, and the Naval Research Laboratory, with backgrounds in physics, chemistry, mechanical engineering and materials science. Together they will develop new multiscale modeling tools and apply them to problems in adhesion, nanotribology and nanofluidics that are of both fundamental scientific interest and technological importance.One approach to multiscale modeling will be hierarchical. Results from different scales will be calculated independently, and the outputs used to determine inputs needed at other scales. For example, atomic scalecalculations will provide constitutive relations and boundary conditions for continuum calculations, while continuum calculations determine contact geometries and stresses for atomic calculations. The second approach will involve simultaneous calculations at multiple scales. Specific strategies for linking tight-binding simulations to classical molecular dynamics (MD) simulations, and for linking MD to continuum solid and fluid calculations are described.Studies of adhesion will examine how surface roughness, surface chemistry, and capillary forces affect stiction. This is the major cause of failure in micromachines and becomes more important as device size decreases.Research on nanotribology will start from contact geometries determined in the adhesion studies. Quantitative comparison between continuum mechanics and MD simulations will be performed at different scales to determine how continuum mechanics breaks down and at what scale. The effect of molecular structure of boundary lubricants, surface roughness, and other factors on friction in nanocontacts will be studied. Work on nanofluidics will focus on changes in flow as the mean free path becomes comparable to some dimensions of the flow path, with an emphasis on understanding lubricant transport to and around nanoscale contacts.Participation in the project will give undergraduate and graduate students, midshipmen and postdoctoral fellows a unique multidisciplinary educational experience that will be strengthened by newly developed course sequences. Modeling tools developed by the team will be designed for portability and to be integrated into publicly available simulation tools.***