中文摘要：

非定常流场模型降阶技术的出现，为CFD／CSD耦合数值模拟方法在工程设计中的广泛应用提供了新机遇．在对非线性系统模型降阶理论与方法进行概述的基础上，全面系统地介绍了非定常流场降阶模型的国内外研究进展．按基于系统辨识的降阶模型和基于流场特征结构的降阶模型两大类进行评述，比较了各种降阶模型的优缺点并指出了进一步改进的思路．最后对非定常流场降阶模型的发展趋势和应用前景进行了展望，并指出自适应鲁棒降阶模型是下一代模型降阶技术的发展方向．

英文摘要：

With the development of the large scale numerical simulation, computational fluid dynamics and computational solid mechanics couple simulation becomes the powerful accurate tool in engineering analysis. But the large computation cost postpones its widely application in design. Reduced order model （ROM） for unsteady flow field, with good accuracy, low order and high efficiency, gives an opportunity to CFD/CSD couple simulation in practical design. Based on the description of model reduction theory and method in the view of mathematics, the advances of the reduced order models for unsteady flow field were systematically introduced. The system identification based ROM such as Volterra/ROM, ARMA/ROM, Surrogate ROM, and flow eigen mode based ROM such as POD/ROM, HB/ROM, ND/ROM were reviewed. The advantages and drawbacks were analyzed with the possible direction of their improvements. The trends and prospects of the ROM for unsteady flow field were discussed, with the indication that the next generation ROM will be more robust and adaptive.