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Unsteady characteristics of flow over a realistic heavy vehicle

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Abstract

Large-eddy simulation of turbulent flow around a 1:8 scale 15-ton heavy vehicle model is performed at Reynolds number of 9.1×105 to study unsteady characteristics of the surface forces. The drag coefficient and profiles of the mean streamwise velocity in the wake region are in good agreement with the experimental counterparts. Time histories of the drag, lift, and side forces are collected to analyze the frequency characteristics of forces applied on the vehicle surface. Velocity fluctuations near the vehicle surface are also obtained to study spectral features of the flow field. Results show that fluctuations of the streamwise velocity in the cab roof region are closely related to the drag frequency, whereas wake shedding heavily affects the frequency characteristics of the side force.

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Abbreviations

A :

Frontal area of the vehicle

C D :

Drag coefficient

C L :

Lift coefficient

C S :

Side force coefficient

Ĉ D :

Fourier transformed drag coefficient

Ĉ L :

Fourier transformed lift coefficient

Ĉ s :

Fourier transformed side force coefficient

E uu :

Energy spectra (main flow direction)

E vv :

Energy spectra (width direction)

E ww :

Energy spectra (ground-normal direction)

f :

Frequency

F D :

Drag

F L :

Lift

F S :

Side force

H:

Height of the vehicle

L:

Length of the vehicle

Q:

Q-criterion

S ij :

Strain rate tensor

U :

Streamwise velocity

U ∞ :

Inlet velocity

x :

Main flow direction

y :

Width direction

z :

Ground-normal direction

Δt:

Time difference

ρ :

Air density

Ω ij :

Vorticity tensor

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Acknowledgments

The work was supported by the National Research Foundation of Korea (NRF) under the Grant Numbers NRF-2019K1A 3A1A74107685 and NRF-2021R1A2C2092146.

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Authors and Affiliations

  1. Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, 37673, Korea

    Myeongkyun Kim & Donghyun You

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  1. Myeongkyun Kim
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  2. Donghyun You
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Correspondence to Donghyun You.

Additional information

Myeongkyun Kim received his B.S degree in Mechanical Engineering from Soongsil University in Korea in 2012. He is currently a M.S/Ph.D. integrated course candidate at the Department of Mechanical Engineering, Pohang University of Science and Technology, Korea.

Donghyun You received the M.S. degree in Scientific Computing and Computational Mathematics and the Ph.D. degree in Mechanical Engineering from Stanford University, USA. He is a Professor of the Department of Mechanical Engineering at POSTECH, South Korea. His research interests include fluid mechanics, turbulent flow, and machine learning.

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Kim, M., You, D. Unsteady characteristics of flow over a realistic heavy vehicle. J Mech Sci Technol 36, 4005–4014 (2022). https://doi.org/10.1007/s12206-022-0721-6

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  • DOI: https://doi.org/10.1007/s12206-022-0721-6

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