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arXiv 1903.04099math.AP
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非局部Cahn-Hilliard方程无条件能量稳定的快速标量辅助变量方法

The fast scalar auxiliary variable approach with unconditional energy stability for nonlocal Cahn-Hilliard equation

Zhengguang liu, Aijie Cheng, Xiaoli Li

摘要:

与经典的局部梯度流模型和相场模型相比,非局部模型如非局部Cahn-Hilliard方程和非局部扩散算子能更好地描述相变现象。本文对具有一般非线性势的非局部Cahn-Hilliard方程构造了一种精确有效的标量辅助变量方法。第一个贡献是我们仔细而严格地证明了非局部Cahn-Hilliard模型及其半离散格式的无条件能量稳定性。其次,我们需要关注的是,非局部扩散项的非局部性将导致刚度矩阵几乎是满矩阵,这将产生巨大的计算工作量和内存需求。对于有限差分法的空间离散,我们发现通过应用四个变换算子,非局部算子的离散将导致块Toeplitz-Toeplitz-块(BTTB)矩阵。基于这种特殊的结构,我们提出了一个快速的过程,以减少计算工作量和内存需求。最后,通过几个数值模拟验证了所提方法的有效性和准确性。

英文摘要:

Comparing with the classical local gradient flow and phase field models, the nonlocal models such as nonlocal Cahn-Hilliard equations equipped with nonlocal diffusion operator can describe more practical phenomena for modeling phase transitions. In this paper, we construct an accurate and efficient scalar auxiliary variable approach for the nonlocal Cahn-Hilliard equation with general nonlinear potential. The first contribution is that we have proved the unconditional energy stability for nonlocal Cahn-Hilliard model and its semi-discrete schemes carefully and rigorously. Secondly, what we need to focus on is that the non-locality of the nonlocal diffusion term will lead the stiffness matrix to be almost full matrix which generates huge computational work and memory requirement. For spatial discretizaion by finite difference method, we find that the discretizaition for nonlocal operator will lead to a block-Toeplitz-Toeplitz-block (BTTB) matrix by applying four transformation operators. Based on this special structure, we present a fast procedure to reduce the computational work and memory requirement. Finally, several numerical simulations are demonstrated to verify the accuracy and efficiency of our proposed schemes.

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。

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