论文标题
对具有压力梯度的湍流边界层光谱的新见解
New insight into the spectra of turbulent boundary layers with pressure gradients
论文作者
论文摘要
借助湍流边界层（TBLS）的新的高雷诺数（$ re $ $）数据库，可以详细识别边界层的某些区域，具有更复杂的行为。 In this study we consider a unique database at moderately-high $Re$, with a near-constant adverse pressure gradient (APG) (Pozuelo {\it et al.}, {\it J. Fluid Mech.}, {\bf 939}, A34, 2022), and perform spectral analysis of the Reynolds stresses, focusing on the streamwise component.我们评估了APG TBL的不同区域，将这种情况与零压力级别（ZPG）TBL进行比较，并确定相关的缩放参数以及不同大小的尺度的贡献。在近壁区域的近壁光谱峰的小尺度已使用粘性单元扩展。在APG TBL中，靠近墙壁的最大尺度具有更好的缩放尺度（$δ_{99} $），并且它们受APG的影响很大。在边界层的重叠和唤醒区域中，小能量尺度表现出良好的缩放尺度（$δ^*$），而较大的尺度和外部光谱峰则可以通过边界层厚度更好地缩放。另请注意，光谱外峰尺度的壁正态位置具有位移厚度而不是边界层厚度。这里首次报道了Spectra在APG TBL中表现出的各种量表，并阐明了这些具有巨大的科学和技术重要性流中存在的复杂现象。
With the availability of new high-Reynolds-number ($Re$) databases of turbulent boundary layers (TBLs) it has been possible to identify in detail certain regions of the boundary layer with more complex behavior. In this study we consider a unique database at moderately-high $Re$, with a near-constant adverse pressure gradient (APG) (Pozuelo {\it et al.}, {\it J. Fluid Mech.}, {\bf 939}, A34, 2022), and perform spectral analysis of the Reynolds stresses, focusing on the streamwise component. We assess different regions of the APG TBL, comparing this case with the zero-pressure-gradient (ZPG) TBL, and identify the relevant scaling parameters as well as the contribution of the scales of different sizes. The small scales in the near-wall region up to the near-wall spectral peak have been found to scale using viscous units. In APG TBLs, the largest scales close to the wall have a better scaling with the boundary-layer thickness ($δ_{99}$), and they are significantly affected by the APG. In the overlap and wake regions of the boundary layer, the small energetic scales exhibit a good scaling with the displacement thickness ($δ^*$) while the larger scales and the outer spectral peak are better scaled with the boundary-layer thickness. Also note that the wall-normal location of the spectral outer peak scales with the displacement thickness rather than the boundary layer thickness. The various scalings exhibited by the spectra in APG TBLs are reported here for the first time, and shed light on the complex phenomena present in these flows of great scientific and technological importance.
