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arXiv 1912.09263math.NAcs.NAmath.AP
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相场模型的指数标量辅助变量(E-SAV)方法及其显式计算

The exponential scalar auxiliary variable (E-SAV) approach for phase field models and its explicit computing

Zhengguang Liu, Xiaoli Li

摘要:

本文考虑一类相场模型的指数标量辅助变量(E-SAV)方法来获得能量稳定格式。这种基于非线性自由能势指数形式的辅助变量方法比目前广泛使用的构造能量稳定格式的SAV方法更加有效和适用。第一个贡献是无平方根的辅助变量消除了非线性自由能势的下界限制。然后,我们仔细和严格地证明了半离散格式的无条件能量稳定性。另一个贡献是我们可以完全显式地离散与非线性项相结合的辅助变量。这种修改对于快速计算是非常有效的。此外,还保证了$r$的正性,这对于模型的等价性是非常重要和合理的。此外,对于含有两个或多个未知变量和非线性项的复相场模型,我们构造了一种多重E-SAV(ME-SAV)方法,以增强所提出的E-SAV方法的适用性。经典的SAV和E-SAV方法的比较研究被认为是显示的准确性和效率。最后,我们提出了各种二维数值模拟,以证明稳定性和准确性。

英文摘要:

In this paper, we consider an exponential scalar auxiliary variable (E-SAV) approach to obtain energy stable schemes for a class of phase field models. This novel auxiliary variable method based on exponential form of nonlinear free energy potential is more effective and applicable than the traditional SAV method which is very popular to construct energy stable schemes. The first contribution is that the auxiliary variable without square root removes the bounded from below restriction of the nonlinear free energy potential. Then, we prove the unconditional energy stability for the semi-discrete schemes carefully and rigorously. Another contribution is that we can discrete the auxiliary variable combined with the nonlinear term totally explicitly. Such modification is very efficient for fast calculation. Furthermore, the positive property of $r$ can be guaranteed which is very important and reasonable for the models' equivalence. Besides, for complex phase field models with two or more unknown variables and nonlinear terms, we construct a multiple E-SAV (ME-SAV) approach to enhance the applicability of the proposed E-SAV approach. A comparative study of classical SAV and E-SAV approaches is considered to show the accuracy and efficiency. Finally, we present various 2D numerical simulations to demonstrate the stability and accuracy.

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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