梯度依赖散度型非线性扩散问题的新迭代方法

Novel iteration method for gradient-dependent diffusion problems of divergence type

  • 摘要: 本文针对扩散系数依赖于梯度的散度型非线性扩散问题,提出了一种新的迭代方法,以提高求解效率. 经典 Picard 迭代法在处理此类非线性方程时往往收敛缓慢或不稳定,其原因可能在于该方法无法提升迭代序列的正则性. 为改善迭代序列的正则性,我们首先在偏微分方程层面设计了一种迭代格式,该格式要求每一步迭代求解一个非散度形式的线性扩散问题. 在离散层面,通过对守恒型非线性差分格式进行细致的重构与线性化,既保持了散度形式离散的解结构,又与连续层面的迭代框架相一致. 数值实验表明,本文所提方法在多种问题(包括限流扩散与强非线性扩散)中均表现良好:在许多情形下迭代次数减少一半以上,并在 Picard 迭代失效时仍能收敛,同时保持相当的数值精度. 结果验证了该方法的稳健性与高效性.

     

    Abstract: This paper proposes a new iterative method for divergence-type nonlinear diffusion problems with gradient-dependent coefficients to enhance solution efficiency. The classical Picard iteration often exhibits slow convergence or instability when applied to such nonlinear equations, likely due to its inability to improve the regularity of the iterative sequence. To address this limitation, we first design an iterative scheme at the partial differential equation level, which requires solving a linear diffusion problem in non-divergence form at each step. At the discrete level, through careful reformulation and linearization of the conservative nonlinear difference scheme, the method preserves the solution structure inherent to divergence-form discretization while remaining consistent with the continuous iterative framework. Numerical experiments demonstrate that the proposed method performs well across various problems, including flux-limited and strongly nonlinear diffusion: it reduces the number of iterations by more than half in many cases, achieves convergence even when Picard iteration fails, and maintains comparable numerical accuracy. The results confirm the robustness and efficiency of the proposed approach.

     

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