Structure of turbulent plumes from a momentumless source in a smooth bed
Structure of turbulent plumes from a momentumless source in a smooth bed
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光滑床中无动量源的湍流羽流结构
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发表时间：
2006
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通讯作者：
J. Koseff
中科院分区：
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作者：
J. Crimaldi;J. Koseff
本文在光滑底床的实验室水槽中，研究了边界层非均匀湍流中被动标量羽流的空间发展。标量源位于与床平齐的位置，低动量源设计旨在模拟扩散型标量释放。弱扩散荧光染料被用作标量。采用平面激光诱导荧光（PLIF）技术，以150 μm的空间分辨率记录了烟羽的结构。的平均浓度场的测量结构相比，剪切自由，均匀湍流的解析解。实验室羽流在平均浓度场的空间发展偏离了分析解预测的自相似行为;这种偏离是由于湍流的平均剪切和不均匀性。特别是，被认为是显着的粘性子层上的羽流发展的影响。尽管如此，分析解决方案复制了实验室羽流中看到的一些特征，并且解决方案提出了减少实验室数据的方法，即使在结果偏离分析的情况下。我们还研究了均方根（rms）波动浓度场的空间发展，并使用标量概率密度函数来研究平均浓度和波动浓度之间的关系。
The spatial development of a passive scalar plume is studied within the inhomogeneous turbulence of a boundary layer flow in a recirculating laboratory flume with a smooth bed. The source of the scalar is located flush with the bed, and the low-momentum source design is intended to simulate a diffusive-type scalar release. A weakly diffusive fluorescent dye is used as the scalar. Planar laser-induced fluorescence (PLIF) techniques were used to record the structure of the plume at a spatial resolution of 150 μm. The measured structure of the mean concentration field is compared to an analytical solution for shear-free, homogeneous turbulence. The laboratory plume exhibits spatial development in the mean concentration field that deviates from the self-similar behavior predicted by the analytical solution; this deviation is due to the mean shear and inhomogeneity of the turbulence. In particular, the influence of the viscous sublayer on the plume development is seen to be significant. Nonetheless, the analytical solution replicates some of the features seen in the laboratory plume, and the solution suggests methods of reducing the laboratory data even for cases where the results deviate from the analysis. We also examine the spatial development of the root-mean-square (rms) fluctuating concentration field, and use scalar probability density functions to examine the relationship between the mean and fluctuating concentrations.