arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2004.14379math.APcs.NAmath.NA
收藏

具有尖锐界面的非局部Cahn-Hilliard模型

On a nonlocal Cahn-Hilliard model permitting sharp interfaces

Olena Burkovska, Max Gunzburger

摘要:

提出了一个具有双阱障碍型非光滑势的非局部Cahn-Hilliard模型,该势促进了解中的尖锐界面。为了捕捉粒子之间的长程相互作用,一个非局部的金斯堡-朗道能量泛函的定义,恢复消失的非局部相互作用的经典(本地)模型。与总是导致扩散界面的局部Cahn-Hilliard问题相反,所提出的非局部模型可以导致严格分离成物质的纯相。这里,电势的平滑性的缺乏对于保证上述尖锐界面性质是必要的。在数学上,这引入了额外的不等式约束,以弱形式,导致耦合系统的变分不等式,在每个时间实例可以被重述为约束最优化问题。证明了半离散和时间连续弱解的适定性和正则性,并给出了纯相存在的条件。此外,我们开发的离散化的问题的基础上,有限元和隐式显式时间步长方法,可以有效地实现。最后,我们说明了我们的理论研究结果,通过几个数值实验在一个和两个空间维度,突出本地和非本地解决方案的功能的差异,也尖锐的接口特性的非本地模型。

英文摘要:

A nonlocal Cahn-Hilliard model with a nonsmooth potential of double-well obstacle type that promotes sharp interfaces in the solution is presented. To capture long-range interactions between particles, a nonlocal Ginzburg-Landau energy functional is defined which recovers the classical (local) model for vanishing nonlocal interactions. In contrast to the local Cahn-Hilliard problem that always leads to diffuse interfaces, the proposed nonlocal model can lead to a strict separation into pure phases of the substance. Here, the lack of smoothness of the potential is essential to guarantee the aforementioned sharp-interface property. Mathematically, this introduces additional inequality constraints that, in a weak form, lead to a coupled system of variational inequalities which at each time instance can be restated as a constrained optimization problem. We prove the well-posedness and regularity of the semi-discrete and continuous in time weak solutions, and derive the conditions under which pure phases are admitted. Moreover, we develop discretizations of the problem based on finite elements and implicit-explicit time stepping methods that can be realized efficiently. Finally, we illustrate our theoretical findings through several numerical experiments in one and two spatial dimensions that highlight the differences in features of local and nonlocal solutions and also the sharp interface properties of the nonlocal model.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑