以二维方柱低雷诺数绕流为研究对象，在非定常数值模拟结果的基础上，首先应用本征正交分解（proper orthogonal decomposition， POD）方法得到特征区域流场的低阶模型，获取POD基函数及时间系数分布规律；其次以P OD的低阶模型为基础，实现了对非定常物理场的重构。研究结果表明：①应用文中的数值分析手段，捕捉到了方柱绕流非定常流动特征，且与公开文献结果吻合较好。②对于文中的研究对象，前4阶P OD模态所占波动总能量99�4％，可以用于较准确描述其非定常流场特征；③各阶P OD模态的时间系数之间都有明确的频率与相位关系，其中能量最大的第一对P OD模态对方柱尾迹流动的波动频率和幅值起决定作用。④在所研究的雷诺数下，前4阶P OD模态就可以很好地重构流场，这对以后低阶模型的建立有一定的指导意义。%Working on a two-dimensional simulation of flow around a square cylinder at Reynolds number of 100, first we obtained the POD reduced order model of the characteristic region of the flow field, then we acquired the distribution of POD modes and temporal coefficients, and finally we reconstructed the original physical field on the basis of the POD reduced order model. The results and their analysis show preliminary that:(1)according to the nu-merical method applied in this paper, we captured the unsteady flow dynamic characteristics of flow around square cylinder and the results are consistent with literature;(2)for the research object of this paper, the first four POD modes, which accounted for 99�4 percent of total energy fluctuations can describe the characteristics of the unsteady flow field accurately;(3)the time coefficients of each POD mode have definite frequency and phase rela-tionship, and the first pair of POD modes with the biggest energy decide the flow fluctuation frequency and ampli-tude of square cylinder wake;(4)for the research of Reynolds number in this paper, the first four POD modes can reconstruct the flow field very well, providing certain significance for the future establishment of POD reduced order model.
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