Large-eddy simulations of a skewed bump are performed with the bump at angles of $10^{\circ }$ and $50^{\circ }$ with respect to the free stream. The wake has a large separation bubble and unsteady vortex structures that are highly sensitive to the bump angle. The $10^{\circ }$ bump has secondary separation with forward-facing flow in the main separation bubble. The Reynolds stress suggests large-scale motions in the wake, but are insufficient to understand the shedding dynamics. The quasi-periodic shedding cycle is reconstructed using spectral proper orthogonal decomposition. For the $10^{\circ }$ case, opposite-sign streamwise vortices are alternately advected downstream in the wake, but only a single vortex is distinguishable in the $50^{\circ }$ case. The wake streamwise velocity pulses twice each cycle in the $10^{\circ }$ bump, but once per cycle in the $50^{\circ }$ bump. The separation bubble and wake oscillate in the spanwise direction. Conditional averaging shows that the vortices are associated with low streamwise velocity and high turbulence. Surface pressures on the bump have negatively skewed distributions in regions on the upstream face and in the separation bubble. In the separation bubble, fluctuations associated with the shedding cycle contribute to the negative skewness.

中文翻译：

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斜凸块上非定常尾流动力学和几何灵敏度的大涡模拟研究

倾斜颠簸的大涡模拟是在相对于自由流的角度为 $10^{\circ }$ 和 $50^{\circ }$ 的颠簸进行的。尾流具有大的分离气泡和不稳定的涡旋结构，对碰撞角高度敏感。$10^{\circ }$ 凸起在主分离气泡中具有前向流动的二次分离。雷诺应力表明尾迹中有大规模运动，但不足以理解脱落动力学。准周期性脱落周期是使用频谱适当的正交分解重建的。对于 $10^{\circ }$ 的情况，相反符号的流向涡流在尾流中交替向下游平流，但在 $50^{\circ }$ 的情况下，只有一个涡流是可区分的。在 $10^{\circ }$ 颠簸中，尾流流向速度每个周期脉冲两次，但是在 $50^{\circ }$ 的颠簸中每个周期一次。分离气泡和尾流在展向方向上振荡。条件平均表明涡流与低流向速度和高湍流有关。凸块上的表面压力在上游面和分离气泡中的区域呈负偏斜分布。在分离气泡中，与脱落周期相关的波动会导致负偏度。