Turbulent dispersion of passive concentration released from a vertical line source in a fully-developed channel flow is studied using direct numerical simulation (DNS). The investigation into the turbulent transport processes of the momentum and concentration is conducted in both physical and spectral spaces, based on a systematic analysis of the statistical moments of the velocity and concentration fields, probability density functions (PDFs) of the concentration fluctuations, and the characteristic wavelengths of energetic eddies that dominate turbulent mixing processes. It is observed that the plume development experiences turbulent convective- and diffusive-stages through a comparative study of the spatial and temporal scales of the velocity and concentration fields. It is also observed that the meandering ratio is small near the ground and within the turbulent diffusive stage, and PDFs of concentration fluctuations are sensitive to both the wall-normal distance and the downstream distance from the concentrated line source.

使用直接数值模拟 (DNS) 研究了在完全发展的通道流中从垂直线源释放的被动浓度的湍流分散。基于对速度场和浓度场的统计矩、浓度波动的概率密度函数 (PDF) 和主导湍流混合过程的高能涡流的特征波长。通过对速度场和浓度场的空间和时间尺度的比较研究，观察到羽流发展经历了湍流对流和扩散阶段。