Aerodynamic Analysis of a Spoiler Using CFD

Authors

  • Lah Anyie Alistar Department of Mechanical Engineering, Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Johor, Malaysia
  • Ahmad Danish Syazwan Mazzri Department of Mechanical Engineering, Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Johor, Malaysia
  • Alicia Jia Qi Lai Department of Mechanical Engineering, Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Johor, Malaysia
  • Calvin Fredrick Department of Mechanical Engineering, Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Johor, Malaysia

DOI:

https://doi.org/10.37934/sjotfe.10.1.1219a

Keywords:

Aerodynamic, automotive spoiler, CFD, ANSYS Fluent, downforce, drag reduction, velocity contour, turbulence modelling, k-ω SST, external flow

Abstract

Automotive spoilers are aerodynamic devices designed to modify airflow around a vehicle's body, primarily to reduce drag and increase downforce, thereby improving vehicle stability and fuel efficiency at high speeds. This study presents a Computational Fluid Dynamics (CFD) investigation of the aerodynamic performance of a rear spoiler using ANSYS Fluent 2026 R1. The spoiler geometry, with a cross-sectional area of 6557.84 mm², a face-face offset of 210 mm, and a height of 70 mm, was modelled and simulated at three freestream inlet velocities: 20 m/s (72 km/h), 40 m/s (144 km/h), and 80 m/s (288 km/h). A polyhedral mesh was employed, with refined inflation layers around the spoiler surface to resolve boundary-layer effects accurately. The k-ω SST turbulence model was applied for all cases. Velocity contour and streamline results reveal that flow accelerates significantly over the upper surface of the spoiler at all speeds, generating a region of elevated velocity above the spoiler and a distinct low-velocity wake region downstream of the trailing edge. As inlet velocity increases from 20 m/s to 80 m/s, the maximum local velocity rises proportionally (approximately 32.49 m/s, 66.83 m/s, and 136.1 m/s, respectively), consistent with inviscid scaling. Recirculation structures and vortex formations in the spoiler wake become progressively more pronounced at 80 m/s. The results demonstrate that the spoiler geometry effectively redirects airflow, supporting downforce generation. This study validates the use of ANSYS Fluent for external automotive aerodynamics and provides a foundation for geometry optimisation of spoiler profiles.

Author Biographies

Lah Anyie Alistar, Department of Mechanical Engineering, Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Johor, Malaysia

cd220027@student.uthm.edu.my

Ahmad Danish Syazwan Mazzri, Department of Mechanical Engineering, Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Johor, Malaysia

ad220110@student.uthm.edu.my

Alicia Jia Qi Lai, Department of Mechanical Engineering, Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Johor, Malaysia

ad220157@student.uthm.edu.my

Calvin Fredrick , Department of Mechanical Engineering, Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Johor, Malaysia

cd220086@student.uthm.edu.my

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Published

2026-09-29

Issue

Vol. 10 No. 1: September (2026)

Section

Articles