Analysis of the Unsteady Wakes of Heavy Trucks in Platoon Formation and Their Potential Influence on Energy Savings

Research output: Contribution to conferencePaperpeer-review

2 Scopus Citations


The authors present transient wind velocity measurements from two successive, well-documented truck platooning track-test campaigns to assess the wake-shedding behavior experienced by trucks in various platoon formations. Utilizing advanced analytics of data from fast-response (100-200-Hz) multi-hole pressure probes, this analysis examines aerodynamic flow features and their relationship to energy savings during close-following platoon formations. Applying Spectral analysis to the wind velocity signals, we identify the frequency content and vortex-shedding behavior from a forward truck trailer, which dominates the flow field encountered by the downstream trucks. The changes in dominant wake-shedding frequencies correlate with changes to the lead and follower truck fuel savings at short separation distances. All followers experience a reduction in wake-shedding frequency at following distances less than 20 m - the same zone where lead trucks experience fuel savings/drag reductions and where followers experience a reduction in platooning benefits. The dominant vortex-shedding frequency decreased by upwards of 35% in this region. Additionally, the third truck in a platoon is shown to experience a lower wake-shedding frequency than the second vehicle in either a two- or three-truck platoon. The correlation of changes in the vortex-shedding frequency to trends in drag reduction, and the associated energy savings, suggest that these phenomena may be related and may provide an opportunity for improving the efficiency potential of truck platooning.

Original languageAmerican English
Number of pages11
StatePublished - 2021
EventSAE 2021 WCX Digital Summit - Virtual, Online, United States
Duration: 13 Apr 202115 Apr 2021


ConferenceSAE 2021 WCX Digital Summit
Country/TerritoryUnited States
CityVirtual, Online

Bibliographical note

Publisher Copyright:
© 2021 Alliance for Sustainable Energy, LLC; National Research Council Canada.

NREL Publication Number

  • NREL/CP-5400-78552

Other Report Number

  • SAE Paper No. 2021-01-0953


  • adaptive cruise control (ACC)
  • connected and automated vehicle
  • cooperative ACC (CACC)
  • heavy-duty truck fuel economy
  • heavy-duty truck partial automation
  • heavy-duty truck platooning
  • Spectral analysis
  • vehicle control performance
  • vortex shedding


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