An IDDES study of the near-wake flow topology of a simplified heavy vehicle  

作　　者：Jie Zhang Zhanhao Guo Shuai Han Siniša Krajnovi′c John Sheridan Guangjun Gao 

机构地区：[1]Key Laboratory of Traffic Safety on Track of Ministry of Education,School of Traffic&Transportation Engineering,Central South University,Changsha 410075,China [2]Joint International Research Laboratory of Key Technology for Rail Traffic Safety,Central South University,Changsha 410075,China [3]National&Local Joint Engineering Research Center of Safety Technology for Rail Vehicle,Central South University,Changsha 410075,China [4]Department of Mechanics and Maritime Sciences,Chalmers University of Technology,Gothenburg 41296,Sweden [5]Department of Mechanical and Aerospace Engineering,Monash University,Clayton,Victoria 3800,Australia.

出　　处：《Transportation Safety and Environment》2022年第2期105-122,共18页交通安全与环境（英文）

基　　金：the Initial Funding of Specially ap-pointed Professorship of Central South University,China(Grant No.202045014);Natural Science Foundation of Hunan Province,China(Grant No.2020JJ4737).

摘　　要：The complex wake flow of a GTS(ground transportation system)model contributes to large percentage of the aerodynamic drag force.Therefore,predicting accurate wake flow will help carry out the drag reduction strategies.In this paper,the near-wake flow topology of the GTS was studied at Re=2.7×104 to assess the capability of a hybrid RANS/LES(Reynolds-averaged Navier–Stokes/large eddy simulation)approach,known as IDDES(improved delayed detached eddy simulation).The current study also aims to understand the effects of different computational parameters,e.g.the spatial resolution,time step,residual level,discretization scheme and turbulence model,on this asymmetrical wake flow configuration.A comparison of IDDES with previous water channel tests,wellresolved LES,partially averaged Navier–Stokes and URANS(unsteady RANS)was included to better understand the benefits of this hybrid RANS/LES approach.The results show that on the medium and fine grids,the IDDES produces an asymmetrical flow topology(known as flow state I)in the near-wake of the vertical midplane,as reported in previous studies.The recommended parameters for the time step(1×10^(–4 )s)and residual level(1×10^(–4))provide sufficient accuracy of wake predictions to show good agreement with experiments.For the convective term of the momentum equation in IDDES,the bounded central difference discretization scheme is proposed to be adopted for discretization.Additionally,URANS cannot accurately capture this asymmetrical flow field.IDDES proves to be capable of predicting thewake flowfield of this simplified heavy vehicle with high accuracy.All obtained conclusions can provide references for the aerodynamic drag reduction of the GTS.

关 键 词：Heavy vehicle Asymmetrical wakes IDDES Computational parameter 

分 类 号：U270.1[机械工程—车辆工程]