A Novel Lagrange Multiplier Approach with Relaxation for Gradient Flows

A Novel Lagrange Multiplier Approach with Relaxation for Gradient Flows

Year:    2024

Author:    Zhengguang Liu, Xiaoli Li

CSIAM Transactions on Applied Mathematics, Vol. 5 (2024), Iss. 1 : pp. 110–141

Abstract

In this paper, we propose a novel Lagrange multiplier approach, named zero-factor (ZF) approach to solve a series of gradient flow problems. The numerical schemes based on the new algorithm are unconditionally energy stable with the original energy and do not require any extra assumption conditions. We also prove that the ZF schemes with specific zero factors lead to the popular SAV-type method. To reduce the computation cost and improve the accuracy and consistency, we propose a zero-factor approach with relaxation, which we named the relaxed zero-factor (RZF) method, to design unconditional energy stable schemes for gradient flows. The RZF schemes can be proved to be unconditionally energy stable with respect to a modified energy that is closer to the original energy, and provide a very simple calculation process. The variation of the introduced zero factor is highly consistent with the nonlinear free energy which implies that the introduced ZF method is a very efficient way to capture the sharp dissipation of nonlinear free energy. Several numerical examples are provided to demonstrate the improved efficiency and accuracy of the proposed method.

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Journal Article Details

Publisher Name:    Global Science Press

Language:    English

DOI:    https://doi.org/10.4208/csiam-am.SO-2022-0048

CSIAM Transactions on Applied Mathematics, Vol. 5 (2024), Iss. 1 : pp. 110–141

Published online:    2024-01

AMS Subject Headings:    Global Science Press

Copyright:    COPYRIGHT: © Global Science Press

Pages:    32

Keywords:    Lagrange multiplier approach zero-factor approach gradient flows relaxation energy stable numerical examples.

Author Details

Zhengguang Liu

Xiaoli Li