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首页> 外文期刊>International Journal of Heat and Fluid Flow >DNS study of passive plume interference emitting from two parallel line sources in a turbulent channel flow
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DNS study of passive plume interference emitting from two parallel line sources in a turbulent channel flow

机译：在湍流通道中从两个平行线源发出的被动羽状干扰的DNS研究

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Turbulent mixing of dual plumes emitting simultaneously from line sources in a turbulent channel flow has been studied using direct numerical simulation (DNS). Three test cases have been compared to investigate the effects of the source separation on turbulent mixing of the two instantaneous plumes. The dispersion and interference of dual plumes are investigated in both physical and spectral spaces, which include an analysis of statistical moments of the concentration field, cross-correlation between the two instantaneous plumes, pre-multiplied spectra of the velocity and concentration fields, and co-spectrum and coherency spectrum of the dual plumes. As the downstream distance from the line source increases, the plume development associated with a single source emission transitions from a turbulent convective stage to a turbulent diffusive stage. It is observed that a plume released from a ground-level source reaches the turbulent diffusive stage faster than that released from an elevated source. It is also observed that a smaller separation between the two line sources tends to facilitate a more rapid growth in the cross-correlation coefficient of two instantaneous plumes. In the near-source region, the maximum coherency spectrum is produced at lower frequencies indicating that dual-plume mixing is dominated by the external flapping effects of large-scale eddy motions. However, in the far downstream region of the sources, the coherency spectrum in the higher frequency range increases significantly, indicating that the spread of the total plume is larger than all scales of turbulent eddies, such that they all contribute to the in-plume mixing of the dual plumes.
机译：已经使用直接数值模拟（DNS）研究了从湍流通道中同时从线源发出的双羽的湍流混合。比较了三个测试案例，以研究源分离对两个瞬时羽流湍流混合的影响。研究了物理空间和光谱空间中双羽的弥散和干扰，包括分析浓度场的统计矩，两个瞬时羽之间的互相关，速度场和浓度场的预乘谱以及羽的光谱和相干光谱。随着与线源下游距离的增加，与单源排放相关的羽流发展从湍流对流阶段过渡到湍流扩散阶段。可以观察到，从地源释放的烟流到达湍流扩散阶段的速度比从高位排放源释放的烟流更快。还观察到，两个线源之间的较小间隔趋向于促进两个瞬时羽流的互相关系数的更快的增长。在近源区域，在较低的频率处产生最大的相干谱，这表明双螺旋混合主要受大规模涡旋运动的外部拍动影响。但是，在源的最下游区域，较高频率范围内的相干谱显着增加，这表明总羽流的散布大于所有湍流涡流的比例，因此它们都有助于在管内混合双羽。

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