【摘要】：對(duì)雷諾數(shù)Re=100下的圓柱繞流非定常流場(chǎng)進(jìn)行數(shù)值模擬,分別采用DMD方法和POD方法對(duì)圓柱繞流卡門渦街發(fā)展過程中的不穩(wěn)定平衡階段、過渡階段以及穩(wěn)定極限環(huán)階段進(jìn)行穩(wěn)定性分析。分析結(jié)果表明:DMD方法準(zhǔn)確地提取了不穩(wěn)定平衡階段和過渡階段中的不穩(wěn)定模態(tài)以及頻率,在穩(wěn)定極限環(huán)階段準(zhǔn)確提取了脫落渦模態(tài)及其高階諧波模態(tài)和頻率。DMD方法不僅可以高效提取主要流場(chǎng)結(jié)構(gòu)模態(tài)和頻率,且可分析相應(yīng)模態(tài)的穩(wěn)定性,從而得到動(dòng)力學(xué)系統(tǒng)在時(shí)間和空間上的主要特征。POD方法中較少的模態(tài)包含流場(chǎng)絕大部分的能量,通過對(duì)模態(tài)系數(shù)進(jìn)行FFT分析,可得到模態(tài)頻率,但有時(shí)會(huì)存在多個(gè)頻率耦合的模態(tài),且POD方法無法判斷所提取模態(tài)的穩(wěn)定性,因此,POD方法主要得到的是動(dòng)力學(xué)系統(tǒng)在空間上的主要特征。另外,DMD方法對(duì)流動(dòng)類型范圍的適用性更廣。因此,在對(duì)復(fù)雜動(dòng)力學(xué)系統(tǒng)進(jìn)行穩(wěn)定性分析時(shí),DMD方法更具有優(yōu)勢(shì)。
[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.
【作者單位】： 西北工業(yè)大學(xué)航空學(xué)院;
【基金】：國(guó)家自然科學(xué)基金(11272264)資助
【分類號(hào)】：O357.5

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