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An investigation on the switching of asymmetric wake flow and the bi-stable flow states of a simplified heavy vehicle
Engineering Applications of Computational Fluid Mechanics ( IF 6.1 ) Pub Date : 2022-10-06 , DOI: 10.1080/19942060.2022.2130432
Jie Zhang, Fan Wang, Shuai Han, Tianxiang Huang, Guangjun Gao, Jiabin Wang

This study investigates the effect of aspect ratios (Ra*) on the wake bi-stability behind the GTS model using improved delayed-detached eddy simulation (IDDES) at a Reynolds number of 2.7×104. Eight cases with Ra* in the range of Ra*∈[0.5, 2.0] have been considered to investigate the asymmetric wake flow and the corresponding aerodynamic response. The primary objective of this study is to reveal the mechanism of the Ra* effects on the GTS’s flow topology, asymmetric wake flow and the bi-stable flow switching process. The accuracy of the numerical method has been validated by comparing the recirculation bubble, vortex core and aerodynamic drag with those obtained from the previous large-eddy simulation study and the water channel experiment. The results show that three typical flow topologies (FT-I, FT-II and FT-III) are classified according to the drag coefficient and the length relation between the vertical and horizontal recirculation region. The vertical and horizontal asymmetric characteristics can be transformed between two adjacent flow topologies. Moreover, a switching process of the bi-stable wake flow is also observed as Ra* is equal to 0.71. Additionally, the ground motion can reverse the dominated flow state and inhibiting the corresponding switching process.



中文翻译:

简化重型车辆不对称尾流切换及双稳态流态研究

本研究使用雷诺数为 2.7×10 4的改进延迟分离涡模拟 (IDDES) 研究纵横比 ( Ra *) 对 GTS 模型背后的尾流双稳定性的影响。Ra * 在Ra *∈[0.5, 2.0] 范围内的8 个案例已被考虑用于研究不对称尾流和相应的气动响应。本研究的主要目的是揭示Ra的机制。* 对 GTS 的流拓扑、不对称尾流和双稳态流切换过程的影响。通过将再循环气泡、涡芯和气动阻力与以往大涡模拟研究和水道试验得到的数值进行比较,验证了数值方法的准确性。结果表明,根据阻力系数和垂直和水平再循环区域之间的长度关系,将三种典型的流动拓扑(FT-I、FT-II和FT-III)分类。垂直和水平不对称特性可以在两个相邻流拓扑之间转换。此外,还观察到双稳态尾流的切换过程为Ra*等于 0.71。此外,地面运动可以逆转主导流动状态并抑制相应的切换过程。

更新日期:2022-10-06
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