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

0103408Robins本提案是应《纳米科学与工程》(NSF 00-119)征集而提交的。这个纳米尺度跨学科研究团队汇集了来自研究型大学(约翰·霍普金斯大学)、海军学院和海军研究实验室的研究人员，他们具有物理、化学、机械工程和材料科学方面的背景。他们将共同开发新的多尺度建模工具，并将它们应用于具有基本科学兴趣和技术重要性的粘合、纳米摩擦学和纳米流体问题。多尺度建模的一种方法将是分层的。来自不同比例尺的结果将独立计算，产出将用于确定其他比额表所需的投入。例如，原子尺度计算将为连续介质计算提供本构关系和边界条件，而连续介质计算将为原子计算确定接触几何和应力。第二种方法将涉及多个尺度的同时计算。描述了将紧束缚模拟连接到经典分子动力学(MD)模拟，以及将MD连接到连续的固体和流体计算的具体策略。附着力的研究将考察表面粗糙度、表面化学和毛细管力如何影响粘性。这是微型机械故障的主要原因，随着器件尺寸的减小，这一点变得更加重要。纳米摩擦学的研究将从粘着研究中确定的接触几何开始。连续介质力学和MD模拟之间的定量比较将在不同的尺度上进行，以确定连续介质力学是如何分解的，以及在什么尺度上。将研究边界润滑剂的分子结构、表面粗糙度和其他因素对纳米接触中摩擦的影响。纳米流体学的工作将侧重于流动的变化，因为平均自由程变得与流动路径的某些维度相当，重点是了解润滑剂向纳米级接触和周围的输送。参与该项目将给本科生和研究生、学员和博士后带来独特的多学科教育经验，新开发的课程序列将加强这一经验。该团队开发的建模工具将设计为可移植性，并集成到公共可用的模拟工具中。*

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.***