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

Jie Zhang, Zhanhao Guo, Shuai Han, Siniša Krajnović, John Sheridan, Guangjun Gao

Research output: Contribution to journalArticleResearchpeer-review

23 Citations (Scopus)

Abstract

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, well-resolved 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 the wake flow field of this simplified heavy vehicle with high accuracy. All obtained conclusions can provide references for the aerodynamic drag reduction of the GTS.

Original languageEnglish
Article numbertdac015
Number of pages18
JournalTransportation Safety and Environment
Volume4
Issue number2
DOIs
Publication statusPublished - 1 Jun 2022

Keywords

  • Asymmetrical wakes
  • Computational parameter
  • Heavy vehicle
  • IDDES

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