Two flow cases for high speed train models with different lengths have been numerically computed by performing the improved delayed detached-eddy simulation. Based on the Omega method and turbulence production (TP) distribution, the relations between the shear flow and vortices in the near turbulent wake of a high speed train have been comparatively analyzed. First, in the wake region immediately close to the tail, the boundary layer separation plays significant roles. And the mechanism makes shear deformation prominent in the region with the formed vortices. Moreover, the shear layers are pertinent to the boundary-layer thicknesses and help to the TP distribution. However, the shear-dominated region is very limited due to high dissipation. One the other hand, a vast majority of the vortices captured with the parameter Omega increasing in the downstream region away from the tail. And the TP distributions are stable at different streamwise positions, though obviously decreased. They are greatly attributed to the mean strain rate in the horizontal plane. Meanwhile, the vortical vorticity is thought to be the dominant component inside the vortex cores, although the shear becomes weaker. And thus the turbulence itself can be spatially sustained due to the relatively stable vortex structure. Moreover, the weak shear is believed to depend upon the interaction between the vortices and the ground.

通过执行改进的延迟分离涡模拟，对不同长度的高速列车模型的两种流动情况进行了数值计算。基于Omega方法和湍流产生(TP)分布，对比分析了高速列车近湍流尾流中剪切流与涡流的关系。首先，在紧靠尾部的尾流区域中，边界层分离起着重要作用。并且该机制使得涡旋形成区域的剪切变形显着。此外，剪切层与边界层厚度有关，有助于 TP 分布。然而，由于高耗散，剪切主导区域非常有限。另一方面，在远离尾部的下游区域，随着参数 Omega 的增加，捕捉到的绝大多数涡流。TP 分布在不同流向位置稳定，但明显下降。它们很大程度上归因于水平面的平均应变率。同时，虽然剪切变弱，但涡旋涡度被认为是涡核内部的主要成分。因此，由于相对稳定的涡流结构，湍流本身可以在空间上持续。此外，据信弱剪切取决于涡流和地面之间的相互作用。同时，虽然剪切变弱，但涡旋涡度被认为是涡核内部的主要成分。因此，由于相对稳定的涡流结构，湍流本身可以在空间上持续。此外，据信弱剪切取决于涡流和地面之间的相互作用。同时，虽然剪切变弱，但涡旋涡度被认为是涡核内部的主要成分。因此，由于相对稳定的涡流结构，湍流本身可以在空间上持续。此外，据信弱剪切取决于涡流和地面之间的相互作用。