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题名	分子动力学与连续介质力学耦合模型的研究及应用; Study and application of hybrid computation scheme adjoining molecular dynamics and continuum mechanics
作者	李玉秀
学位类别	博士
答辩日期	2009-01-06
授予单位	中国科学院广州能源研究所
授予地点	广州能源研究所
导师	徐进良
关键词	分子动力学 跨尺度耦合 界面边界条件
其他题名	Study and application of hybrid computation scheme adjoining molecular dynamics and continuum mechanics
中文摘要	Boundary condition on the solid-fluid interface is one of the key scientific issues relating to the energy conversion, storage, and transfer in energy systems. It is an old but not well-solved problem. Study of such a problem not only is important in science, but also has wide engineering applications. Specifically, in the fast developing micro/nano systems, the channel size covers nanometer, micron, and even millimeter scale. Meanwhile, the solid and fluid material, wettability, and surface roughness etc. all have important influences on the boundary conditions, making the problem very complicated. This thesis presented studies on the boundary conditions from the following four related aspects. A complete set of characteristic parameters governing the boundary conditions was established, identifying the internal relationship among these parameters. Within the developed parameter sets, a three-atom-model was proposed, from the interactions of the atomes and the short range interaction characteristic, physically. A criterion number controlling the boundary conditions was achieved, which is related to the surface wettability. Physically, the criterion number of 0.757 stands for the hydrophilic surface, corresponding to the non-slip or locking boundary conditions. Deviation from 0.757 of the criterion number represents the hydrophobic surface, corresponding to the slip boundary conditions. A molecular dynamics simulation code was developed, which could compute the flow field of the micro Couette and Poiseuille flow. The computation results verified the propsed three-atom-model. The computation also reproduces the three types of boundary conditions of slip, non-slip, and locking. The non-Newton flow behavior at high shear rates was found. A hybrid computation code adjoining the molecular dynamics and continuum fluid mechanics was developed, which could calculate the flow field with the channel size from nanometer, micron, to millimeter. The domain decomposition method was proposed. Three regions were subdivided: the MD region close to the solid-fluid surface, the coupling region, and the NS region far away from the surface. The strict mathematic formulation in each region was given. The constraint criterion was proposed in the coupling region, ensuring the parameter continuous in the space coordinate, and the convergence in the time series. The boundary conditions with the channel size from micro/nano meter to macroscale were studied using the developed code. The constant slip length principle was found, i.e., the slip lengths are not depended on the channel size, but only depended on the solid-fluid interactions. Such a principle stands for the real physical mechanism, which is also called as the absouleteness of the boundary conditions. On the other hand, the slip velocities at the solid-fluid surface approach zero when the channel size is continuously increased, which is named as the relativity of the boundary conditions, standing for the appearance. Physically, there is no transfer from micro to macro regarding the boundary condition issue. The absoluteness and relativity of the boundary conditions are the two aspects of the problem, providing the guideline for the design of the micro/nano systems.
语种	中文
公开日期	2011-07-10 ; 2011-07-15
页码	128
内容类型	学位论文
源URL	[http://ir.giec.ac.cn/handle/344007/4059]
专题	中国科学院广州能源研究所
推荐引用方式 GB/T 7714	李玉秀. 分子动力学与连续介质力学耦合模型的研究及应用, Study and application of hybrid computation scheme adjoining molecular dynamics and continuum mechanics[D]. 广州能源研究所. 中国科学院广州能源研究所. 2009.

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