ITR/AP (CHE): Mutliscale Treatment of Fluid-Solid Interfaces: Development of Hybrid Monte Carlo and Finite Element Code

0112929 Zheng ITR/AP小团体奖支持开发高效和强大的计算方法，用于模拟涉及不同长度尺度现象的物理系统。 其结果将为计算机辅助设计、分析和建模提供重要的依据。一个经典的例子是一个系统，涉及流体-固体界面的复杂几何形状的尺度从分子到宏观。一方面，基于连续近似的计算建模方法（例如，有限元和有限差分技术）能够仅在比界面处流体密度明显变化的典型距离长得多的波长处描述机械响应。另一方面，整个系统太大，无法用完全原子化的模拟来处理，这种模拟将同时包括所有尺度的响应。为了解决这个问题的混合蒙特卡罗有限元方案，其中流体分子在界面处被明确地处理，而固体处理的连续技术，将被应用。一个“减少”的描述，其中的随机变量包括thefluid分子的位置和覆盖固相的有限元网格的节点将被开发。蒙特卡罗的随机性使其成为一种高效的并行计算方案，这对于模拟真实世界的系统至关重要。一个多学科的团队已经组建起来承担这个为期三年的项目，其预期成果是一个强大的计算方案，用于分析现实的流体-固体系统的热机械响应，其中分子异质界面与宏观连续体的耦合起着至关重要的作用。

0112929ZhengThis ITR/AP Small Group Award supports development of efficient and robust computational methods for simulating physical systems involving phenomena at drastically different length scales. The results will serve an important need in computer-aided design, analysis andmodeling. A classic example is a system that involves fluid-solid interfaces with complex geometries on scales ranging from molecular to macroscopic. On one hand, computational modeling approaches based on continuum approximations (e.g., finite-element and finite-difference techniques) are capable of describing mechanical responses only at wavelengths much longer than the typical distances over which the fluid density at interfaces varies appreciably. On the other hand, the whole system is far too large to be treated by a fully atomistic simulation that would encompass responses at all scales simultaneously. To address this problem a hybrid Monte Carlo-finite element scheme, in which fluid molecules at the interface are treated explicitly, while the solid is handled by continuum techniques, will be applied. A "reduced" description in which the stochastic variables consist of the positions of thefluid molecules and the nodes of the finite-element mesh covering the solid phase will be developed. The stochastic nature of Monte Carlo lends itself to an efficient parallel computing scheme, which is crucial for simulating real-world systems. A multi-disciplinary team has been assembled to undertake the three-year project, the expected outcome of which is a powerful computational scheme for analyzing the thermomechanical response of realistic fluid-solid systems in which the coupling of the molecularly heterogeneous interfaces to the macroscopic continuum plays an essential role.***