Multiscaling properties on sequences of turbulent plumes images
Multiscaling properties on sequences of turbulent plumes images
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DOI：
10.1016/j.chaos.2017.10.011
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发表时间：
2017-12
影响因子：
7.8
通讯作者：
P. López;A. Tarquis;A. Matulka;Benjamín Skadden;J. Redondo
中科院分区：
文献类型：
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作者：
P. López;A. Tarquis;A. Matulka;Benjamín Skadden;J. Redondo
在不同的实验条件（源Ho的高度），其中的措施是图像的灰度值（从0到255）的有限范围尺度上的羽流浓度图像的多重分形分析，被施加到研究其结构随着时间的推移。多重分形谱呈现特征性的倒U形，并在所有Ho中呈现相似的演化。Hölder指数（Δα）的变化在不同时刻呈现不同的幅度，并随时间的延长而增大。光谱的对称性（Δf）随时间降低，达到负值（从左手不对称发展到右手不对称）。我们展示了轴向速度（W）随Δα和Δf的不同行为。夹带系数αe与熵维数α1呈线性关系。因此，多重分形谱及其参数可以作为羽流演化的标志，也可以用来研究实验条件的影响。
A multifractal analysis on a finite-range-scale of the plume concentration images at different experimental conditions (the height of the sourceHo), where the measure is the grey value of the image (from 0 to 255), was applied to study its structure through time. The multifractal spectrum showed the characteristic inverse U-shape and a similar evolution in allHo. The variation of the Hölder exponent (Δα) presented different amplitudes at different moments and increased with time. The symmetry of the spectrum (Δf) decreased with time achieving negative values (from left hand asymmetry evolving to right asymmetry). We show the different behaviour of axial velocity (W) with Δαand Δf. There is a linear relation of entrainment coefficient (αe) and the entropy dimension (α1). Therefore, the multifractal spectrum and the derived parameters can be used as markers of plume evolution as well as to study the effect of experimental conditions.