The influence of wavy walls on the transport of a passive scalar in turbulent flows
The influence of wavy walls on the transport of a passive scalar in turbulent flows
复制标题
波状壁对湍流中被动标量传输的影响
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
P. R. von Rohr
中科院分区：
文献类型：
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作者：
S. Kuhn;C. Wagner;P. R. von Rohr
我们进行了一项实验研究，以调查在一个平顶壁和两个不同的复杂表面之间的湍流流动中的被动标量的湍流输运，并描述了不同的表面几何形状对混合性能的影响。为了实现一个均匀和非均匀的参考流的情况下，考虑了两种不同类型的表面几何形状：采用数字粒子图像测速技术（DPIV）和平面激光诱导荧光（PLIF）相结合的方法，研究了两种不同情况下的流动特性，展向和壁面法向速度分量，并评估标量的浓度场。从DPIV和PLIF两者获得统计上足够的图像序列（帧速率4Hz）以计算速度场和标量场的时间平均统计。我们讨论了复杂表面对流场中存在的大尺度结构和被动标量的传输的影响。一个更高的展向扩展的标量羽流相比，平面通道流。由于复杂表面的影响，垂直于平均流动方向的输运量增加，与正弦波形表面相比，两波叠加表面的湍流混合特性增强。这与该表面几何形状的大规模结构的缩放是一致的。
We carry out an experimental study to investigate the turbulent transport of a passive scalar in turbulent flows between a flat top wall and two different complex surfaces and describe the influence of the different surface geometries on the mixing properties.In order to achieve a homogeneous and inhomogeneous reference flow situation two different types of surface geometries are considered: a sinusoidal bottom wall profile and a profile consisting of two superimposed sinusoidal waves.The laboratory investigations were performed by the use of a combined digital particle image velocimetry (DPIV) and planar laser-induced fluorescence (PLIF) technique to examine the spatial variation of the streamwise, spanwise and wall-normal velocity components and to assess the concentration field of the scalar. Statistically sufficient image sequences (frame rate 4 Hz) are obtained from both DPIV and PLIF to calculate time-averaged statistics of the velocity field and the scalar field. We discuss the influence of the complex surfaces on large-scale structures present in the flow field and the transport of the passive scalar. A higher spanwise spreading of the scalar plume is observed compared to plane channel flows. Due to the influence of the complex surfaces a higher transport normal to the mean flow direction is found. The mixing properties of the turbulent flow are enhanced for the surface composed of two superimposed waves compared to the sinusoidal wavy surface. This is consistent with the scaling of large-scale structures found for this surface geometry.