Abstract Multi-ionic reactive transport modeling can provide a better understanding of localized corrosion in iron and steel alloys. However, one-step numerical methods used to solve reactive transport equations in a fully-coupled manner may suffer from poor conditioning and numerical convergences issues. In this paper, a sequential non-iterative approach (SNIA) is developed to enable robust numerical simulation of multi-ionic reactive transport models for localized corrosion. The electro-diffusive mass transport equations are decoupled from the homogeneous equilibrium chemical reactions equations, and are solved sequentially without iteration, leading to a two-step numerical method. The nonlinear mass transport equations are discretized using the standard finite element method, linearized and solved using the Newton-Raphson method. To ensure the non-negativity of ionic concentrations, the nonlinear chemical reactions equations are solved using the Newton-Raphson method together with the under-relaxation technique. Numerical studies, including model comparison, parametric and experimental validation studies, are conducted to simulate localized crevice/cavity corrosion of generic carbon steel and iron-chromium binary alloys and to demonstrate the efficacy of the proposed approach.

中文翻译：

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用于模拟局部腐蚀期间多离子物种反应传输的顺序非迭代方法

摘要 多离子反应输运模型可以更好地了解钢铁合金中的局部腐蚀。然而，用于以完全耦合的方式求解反应输运方程的一步数值方法可能会遇到条件差和数值收敛问题。在本文中，开发了一种顺序非迭代方法 (SNIA)，以便对局部腐蚀的多离子反应输运模型进行稳健的数值模拟。电扩散传质方程与均相平衡化学反应方程解耦，无需迭代即可顺序求解，从而形成两步数值方法。非线性质量传递方程使用标准有限元方法进行离散化，使用 Newton-Raphson 方法进行线性化和求解。为确保离子浓度的非负性，非线性化学反应方程使用牛顿-拉夫森方法和欠松弛技术求解。进行了包括模型比较、参数和实验验证研究在内的数值研究，以模拟普通碳钢和铁铬二元合金的局部缝隙/腔腐蚀，并证明所提出方法的有效性。