流体环境下微纳米纤维的力学性质与动力学行为

The interaction between fluid and micro/nanofibers is of key importance in micro/nanoelectromechancal systems, separation and filtrations. In contrast to macroscopic applications, the fluid-structure interaction at micro/nanoscale is critically defined by the structural and surface properties of micro/nanofibers, interfacial slip, thermal fluctuation and interfiber hydrodynamic coupling, which cannot be captured by continuum mechanics. In this project, we will focus on carbon nanotubes based bundles, fibers and arrays, and develop multiscale methods from atomistic, coarse-grained and continuum models to include hydrodynamic interactions therein. The methods will be applied to investigate mechanical properties and dynamical behavior of micro/nanofibers for mechanosensing, actuating and harvesting devices in fluidic environments, also flow-resistance, flow-induced deformation and fracture of nanostructured fiber-based materials. Experiments will be performed to explore tuning mechanisms of micro/nanostructures, surface functionalization of fibers,fluid and external fields from a practical viewpoint in developing aforementioned devices and materials.

微纳米尺度下流体与纤维结构的相互作用是设计流体环境下的微纳米机械器件以及流动过滤分离材料等应用的理论基础。然而其物理机制受到几何、表面特性、界面滑移、热涨落、纤维间流体动力学耦合等因素的影响，因而难以在连续介质力学基础上加以描述。本项目以碳纳米管等微纳米纤维为对象，通过耦合原子分子、介观粗粒化与宏观连续模型，开发考虑流体动力学相互作用的计算方法，对流体环境下微纳米纤维及其阵列的力学性质与动力学行为以及流场经过微纳米结构材料时的流阻、破坏特性与动力学行为等进行研究。同时开展实验工作，通过对微纳米纤维结构、表面性质、外场环境的调控探讨器件和材料的优化设计。

本工作发展了研究流场环境微纳米结构动力学的数值方法，包括隐式溶剂、分子动力学耦合格子Boltzmann方法、分子动力学耦合耗散粒子动力学三种处理微纳米尺度流体固体耦合的方法；研究了微纳米纤维及其阵列在流体环境下的变形、组装、机械能量传递、运动同步行为；与实验结果结合，提出了流体驱动组装碳纳米纤维结构材料的强度等力学性能与微结构的定量关联模型。具体的研究内容包括流体环境自组装动力学、流体环境微纳米纤维运动同步行为、流场驱动微纳米纤维自组装动力学、流场驱动组装碳纳米管纤维力学性能，以及氧化石墨烯薄膜等由纳米结构组装体在溶剂中的溶胀特性、纳米结构表界面液体结构与动力学特性等相关问题，为微纳米尺度流固耦合的机制提供了较为完整的理解。