动力学模态分解和本征正交分解对圆柱绕流稳定性的分析
发布时间：2018-12-27 06:25
【摘要】：对雷诺数Re=100下的圆柱绕流非定常流场进行数值模拟,分别采用DMD方法和POD方法对圆柱绕流卡门涡街发展过程中的不稳定平衡阶段、过渡阶段以及稳定极限环阶段进行稳定性分析。分析结果表明:DMD方法准确地提取了不稳定平衡阶段和过渡阶段中的不稳定模态以及频率,在稳定极限环阶段准确提取了脱落涡模态及其高阶谐波模态和频率。DMD方法不仅可以高效提取主要流场结构模态和频率,且可分析相应模态的稳定性,从而得到动力学系统在时间和空间上的主要特征。POD方法中较少的模态包含流场绝大部分的能量,通过对模态系数进行FFT分析,可得到模态频率,但有时会存在多个频率耦合的模态,且POD方法无法判断所提取模态的稳定性,因此,POD方法主要得到的是动力学系统在空间上的主要特征。另外,DMD方法对流动类型范围的适用性更广。因此,在对复杂动力学系统进行稳定性分析时,DMD方法更具有优势。
[Abstract]:The unsteady flow field around a cylinder under Reynolds number Re=100 is numerically simulated. The unsteady equilibrium stage of the development of the cylinder around the Carmen vortex street is studied by using the DMD method and the POD method, respectively. The transition stage and the stable limit cycle stage are analyzed. The results show that the unstable modes and frequencies in the unstable equilibrium and transition phases are accurately extracted by the DMD method. The shedding vortex mode and its higher-order harmonic modes and frequencies are accurately extracted at the stable limit cycle stage. The DMD method can not only efficiently extract the modes and frequencies of the main flow field structures, but also analyze the stability of the corresponding modes. Thus, the main characteristics of the dynamic system in time and space are obtained. Less modes in the POD method contain most of the energy of the flow field. Modal frequencies can be obtained by FFT analysis of the modal coefficients. But sometimes there are several frequency coupling modes, and the POD method can not judge the stability of the extracted modes. Therefore, the main characteristics of the dynamic system in space are obtained by the POD method. In addition, the DMD method is more applicable to the flow type range. Therefore, the DMD method has more advantages in the stability analysis of complex dynamical systems.
【作者单位】： 西北工业大学航空学院;
【基金】：国家自然科学基金(11272264)资助
【分类号】：O357.5
[Abstract]:The unsteady flow field around a cylinder under Reynolds number Re=100 is numerically simulated. The unsteady equilibrium stage of the development of the cylinder around the Carmen vortex street is studied by using the DMD method and the POD method, respectively. The transition stage and the stable limit cycle stage are analyzed. The results show that the unstable modes and frequencies in the unstable equilibrium and transition phases are accurately extracted by the DMD method. The shedding vortex mode and its higher-order harmonic modes and frequencies are accurately extracted at the stable limit cycle stage. The DMD method can not only efficiently extract the modes and frequencies of the main flow field structures, but also analyze the stability of the corresponding modes. Thus, the main characteristics of the dynamic system in time and space are obtained. Less modes in the POD method contain most of the energy of the flow field. Modal frequencies can be obtained by FFT analysis of the modal coefficients. But sometimes there are several frequency coupling modes, and the POD method can not judge the stability of the extracted modes. Therefore, the main characteristics of the dynamic system in space are obtained by the POD method. In addition, the DMD method is more applicable to the flow type range. Therefore, the DMD method has more advantages in the stability analysis of complex dynamical systems.
【作者单位】： 西北工业大学航空学院;
【基金】：国家自然科学基金(11272264)资助
【分类号】：O357.5
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