An Improved Implicit Eulerian Tangent Algorithm
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摘要: 对于Hessian矩阵正定的情形,在求解二次函数模型信赖域子问题的隐式分段折线算法的基础上,提出一种求解信赖域子问题的改进的隐式Euler切线法,并分析该路径的性质.数值实验表明新算法是有效可行的,且较原算法具有迭代次数少、计算时间短等优点.
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关键词:
- 隐式Euler切线法 /
- 信赖域子问题 /
- 微分方程模型 /
- 无约束优化 /
- 信赖域方法
Abstract: Based on the two-velocity Brinkman-extended Darcy flow model, the characteristics of high speed flow in circular and annular ducts occupied by bidisperse porous media were analyzed. The flow fields of the fracture (f) and porous (p) phases were inherently governed by the 4th-order system of coupled differential equations. The original governing equations were simplified to a 2nd-order system of decoupled differential equations with the normal mode reduction method. Furthermore, the analytical solutions of velocity distributions were readily derived for the f- and p-phases. Results from both the circular and the annular ducts show that an increase in the Darcy number leads to a reduction in not only the flow velocities of the two phases but their difference. However, the flow velocities of the two phases exhibit an opposite trend with the increase of the momentum transfer between the two phases, resulting in a decrease in the velocity difference. -
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