论文标题
湍流开路流的直接数值模拟
Direct Numerical Simulation of Turbulent Open Channel Flow
论文作者
论文摘要
进行摩擦雷诺数$re_τ= 200,400,600 $的湍流开放通道流的直接数值模拟。将他们的结果与封闭的通道数据进行比较，以研究自由表面对湍流通道流的影响。迄今为止，自由表面会影响完全发达的湍流统计数据，以至于速度和涡度在接近时变得高度各向异性。虽然涡度各向异性层在壁单元中缩放，但发现速度可以扩展外流量单元并显示出更大的延伸。此外，通过光谱统计，讨论了自由表面对相干非常大规模运动（VLSM）的影响。发现与闭合通道流相比，SPANWIESS的扩展增加了两倍，而与雷诺数无关。最后，研究了对流场的瞬时实现，以阐明湍流机制，这些机制负责在通道流中自由表面的行为。
Direct numerical simulations of turbulent open channel flow with friction Reynolds numbers of $Re_τ=200,400,600$ are performed. Their results are compared with closed channel data in order to investigate the influence of the free surface on turbulent channel flows. The free surface affects fully developed turbulence statistics in so far that velocities and vorticities become highly anisotropic as they approach it. While the vorticity anisotropy layer scales in wall units, the velocity one is found to scale ith outer flow units and exhibits much larger extension. Furthermore the influence of the free surface on coherent very large-scale motions (VLSM) is discussed through spectral statistics. It is found that the spanwise extension increases by a factor of two compared to closed channel flows independent of the Reynolds number. Finally instantaneous realizations of the flow fields are investigated in order to elucidate the turbulent mechanisms, which are responsible for the behaviour of a free surface in channel flows.
