A wall-bounded turbulent mixing layer flow over an open step: part 2. Unsteady characteristics
A wall-bounded turbulent mixing layer flow over an open step: part 2. Unsteady characteristics
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DOI：
10.1080/14685240601064749
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发表时间：
2007-01-01
影响因子：
1.9
通讯作者：
Sung, H. J.
中科院分区：
文献类型：
--
作者：
Liu, Y. Z.;Ke, F.;Sung, H. J.
研究了开口台阶上有壁面湍流混合层流动的非定常特性。壁面压力波动和速度波动的同时测量分别使用麦克风阵列和X型镀金热线。为了揭示壁面湍流混合层流动的尺度变化结构，采用基于最大重叠离散小波变换（MODWT）的多分辨率分析方法.使用连续小波变换壁压的自相关性提取在频率St = 0.075处的大尺度旋涡结构脱落。在St = 0.076和高次谐波频率St = 0.15和0.29处的涡的对流特征被描述为条件平均速度场和雷诺应力场、壁面压力场的尺度相关以及条件平均壁面压力与速度场之间的相关。在x/H = 15.0时，当大尺度涡结构与壁面接触时，通过开口台阶夹带的流体的流量最高。
The unsteady characteristics of the wall-bounded turbulent mixing layer flow over an open step were investigated. Simultaneous measurements of wall pressure fluctuations and velocity fluctuations were accomplished using a microphone array and X-type gold-plated hotwire, respectively. To elucidate the scale-variant flow structure superimposed on the wall-bounded turbulent mixing layer flow, a multi-resolution analysis based on the maximum overlap discrete wavelet transform (MODWT) was performed. The large-scale vortical structure shedding at the frequency St = 0.075 was extracted using the autocorrelation of the continuous wavelet transformed wall pressure. The convective features of the vortices at St = 0.076 and the higher harmonic frequencies St = 0.15 and 0.29 were delineated in terms of the conditionally averaged velocity field and Reynolds stress field, the scale-variant cross-correlation of the wall pressure field, and the cross-correlation between the conditionally averaged wall pressure and the velocity field. The flow rate of fluid entrained through the open step was the highest when the large-scale vortical structure came into contact with the wall at x/H = 15.0.