A Self-Adaptive Uzawa Block Relaxation Algorithm for Free Boundary Problems
-
摘要: 利用增广Lagrange乘子法和自适应法则,得到求解单侧障碍自由边界问题的自适应Uzawa块松弛法.单侧障碍自由边界问题离散为有限维线性互补问题,等价于一个用辅助变量和增广Lagrange函数表示的鞍点问题.采用Uzawa块松弛算法求解该问题得到一个两步迭代法,主要的子问题为一个线性问题,同时能显式求解辅助变量.由于Uzawa块松弛算法的收敛速度显著依赖于罚参数,而且对具体问题很难选择合适的罚参数.为提高算法的性能,提出了自适应法则,该方法自动调整每次迭代所需的罚参数.数值结果验证了该算法的理论分析.
-
关键词:
- 自由边界 /
- 互补问题 /
- Uzawa块松弛算法 /
- 增广Lagrange函数 /
- 自适应法则
Abstract: A self-adaptive Uzawa block relaxation algorithm, based on the augmented Lagrangian multiplier method and the self-adaptive rule, was designed and analyzed for free boundary problems with unilateral obstacle. The problem was discretized as a finite-dimensional linear complementary problem which is equivalent to a saddle-point one with an augmented Lagrangian function and an auxiliary unknown. With the Uzawa block relaxation method for the problem, a 2-step iterative method was got with a linear problem as a main subproblem while the auxiliary unknown was computed explicitly. The convergence speed of the method highly depends on the penalty parameter, and it is difficult to choose a proper parameter for an individual problem. To improve the performance of the method, a self-adaptive rule was proposed to adjust the parameter automatically per iteration. Numerical results confirm the theoretical analysis of the proposed method. -
[1] 韩渭敏, 程晓良. 变分不等式简介: 基本理论、数值分析及应用[M]. 北京: 高等教育出版社, 2007.(HAN Weimin, CHENG Xiaoliang. Introduction to Variational Inequality: Element Theory, Numerical Analysis and Applications [M]. Beijing: Higher Education Press, 2007.(in Chinese)) [2] GLOWINSKI R. Numerical Methods for Nonlinear Variational Problems [M]. Berlin: Springer-Verlag, 2008. [3] 饶玲. 单调迭代结合虚拟区域法求解非线性障碍问题[J]. 应用数学和力学, 2018,39(4): 485-492.(RAO Ling. Monotone iterations combined with fictitious domain methods for numerical solution of nonlinear obstacle problems[J]. Applied Mathematics and Mechanics,2018,39(4): 485-492.(in Chinese)) [4] LIN Y, CRYER C W. An alternating direction implicit algorithm for the solution of linear complementarity problems arising from free boundary problems[J]. Applied Mathematics and Optimization,1985,13(1): 1-17. [5] BURMAN E, HANSBO P, LARSON M G,et al. Galerkin least squares finite element method for the obstacle problem[J]. Computer Methods in Applied Mechanics and Engineering,2017,313: 362-374. [6] LI X, YUAN D M. Asymptotic approximation method for elliptic variational inequality of first kind[J]. Applied Mathematics and Mechanics(English Edition),2014,35(3): 381-390. [7] YUAN D M, CHENG X L. A meshless method for solving the free boundary problem associated with unilateral obstacle[J]. International Journal of Computer Mathematics,2012,89(1): 90-97. [8] 王光辉, 王烈衡. 基于对偶混合变分形式的Uzawa型算法[J]. 应用数学和力学, 2002,23(7): 682-688.(WANG Guanghui, WANG Lieheng. Uzawa type algorithm based on dual mixed variational formulation[J]. Applied Mathematics and Mechanics,2002,23(7): 682-688.(in Chinese)) [9] GLOWINSKI R, TALLEC P L E. Augmented Lagrangian and Operator-Splitting Methods in Nonlinear Mechanics [M]. Philadelphia: SIAM, 1989. [10] KOKO J. Uzawa block relaxation method for the unilateral contact problem[J]. Journal of Computational and Applied Mathematics,2011,235(8): 2343-2356. [11] HE B S, LIAO L Z, WANG S L. Self-adaptive operator splitting methods for monotone variational inequalities[J]. Applied Numerical Mathematics,2003,94(4): 715-737. [12] 钟艳丽, 严月月, 张守贵. 求解单侧障碍问题的自适应投影方法[J]. 重庆师范大学学报(自然科学版), 2018,35(1): 70-76.(ZHONG Yanli, YAN Yueyue, ZHANG Shougui. A self-adaptive projection method for the unilateral obstacle problem[J]. Journal of Chongqing Normal University(Natural Scienes),2018,35(1): 70-76.(in Chinese)) [13] ZHANG S G. Projection and self-adaptive projection methods for the Signorini problem with the BEM[J]. Applied Mathematics and Computation,2017,74(6): 1262-1273. [14] ZHANG S G, LI X L. A self-adaptive projection method for contact problems with the BEM[J]. Applied Mathematical Modelling,2018,55: 145-159. [15] MARKUS B, SCHRODER A. A posteriori error control of hp-finite elements for variational inequalities of the first and second kind[J]. Computers & Mathematics With Applications,2015,70(12): 2783-2802. [16] ZOSSO D, OSTING B, XIA M, et al. An efficient primal-dual method for the obstacle problem[J]. Journal of Scientific Computing,2017,73(1): 416-437.
点击查看大图
计量
- 文章访问数: 1262
- HTML全文浏览量: 142
- PDF下载量: 522
- 被引次数: 0