Near-wall hot-wire measurements Part II: Turbulence time scale, convective velocity and spectra in the viscous sublayer
Near-wall hot-wire measurements Part II: Turbulence time scale, convective velocity and spectra in the viscous sublayer
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DOI：
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发表时间：
2001
影响因子：
2.4
通讯作者：
B. Khoo;Y. Chew;C. Teo
中科院分区：
文献类型：
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作者：
B. Khoo;Y. Chew;C. Teo
这项工作延续了我们以前的研究，在湍流通道和平板边界层流动中使用近壁热线探头进行了实验。比较分析了粘性子层、缓冲区及以外的壁面剪应力和流向速度脉动的概率密度函数。利用两点相关技术得到了近壁区流向速度脉动的对流速度UC。结果表明，在粘性亚层中，对于槽道流动和边界层流动，Uc分别在13Uτ和15Uτ时基本不变。首次给出了粘性亚层的谱数据，不同流动条件下的归一化谱图在高频或波数下崩塌，从而表明在不同雷诺数下可能存在小尺度普适性。文中还给出了粘性亚层中流向速度脉动的积分时间尺度。
This work continues our previous studies, where experiments were performed in turbulent-channel and flat-plate boundary-layer flows using near-wall hot-wire probes. The probability density function (pdf) of the wall-shear stress and streamwise velocity fluctuations in the viscous sublayer, buffer region and beyond were compared and analyzed. The convective velocity U c of the streamwise velocity fluctuations in the very near-wall region was obtained using a two-point correlation technique. It was found that in the viscous sublayer, U c is approximately constant at 13u τ and 15u τ , respectively, for the channel and boundary-layer flows. Spectra data for the viscous sublayer are presented for the first time, and the normalized spectral plots for different flow conditions collapse at high frequencies or wavenumbers, thus indicating the possible presence of small-scale universality at different Reynolds numbers. The integral time scale corresponding to the streamwise velocity fluctuations in the viscous sublayer is also presented