The Peloton Project: Largest-Ever Sports Simulation Yields Surprising Results

Aerodynamics in a cycling peloton aren’t what you might expect.

A peloton is the main field or group of riders in a road bicycle race like the Tour de France. While it can take different shapes, the peloton’s overall purpose is to take advantage of the effects of slipstreaming, or drafting, behind other riders in the group. Air resistance is the biggest mechanical component preventing cyclists from going faster on flat road, and slipstreaming can save up to 50 percent of their energy.

Or that was the assumption, at least.

The reality is that almost no information exists on aerodynamic resistance for riders in cycling pelotons. Systematic computer simulations or measurements have never been reported before.

Professor Bert Blocken of Eindhoven University of Technology (Netherlands) and KU Leuven (Belgium) set out to fill the information gap.

In partnership with Cray and simulation software vendor ANSYS, Prof. Blocken conducted the first aerodynamic simulation and wind tunnel test of a full peloton of 121 cyclists and, in the process, set a world record in CFD simulation.

With almost 3 billion calculation cells, the Peloton Project simulation was the largest ever in sports and the largest using commercial CFD software anywhere.

Simplified mathematical models commonly assumed the resistance to be reduced to 50 or 70 percent that of an isolated rider. Those numbers are actually 10 times too high. Teams used them to set strategy such as determining when a cyclist should try to escape the peloton. And it could explain why so few breakaways actually succeeded.

Professor Blocken’s study, for the first time, systematically investigated drag reductions in two pelotons of 121 cyclists each. The simulations were validated by four wind tunnel tests, including one with a peloton of 121 models.

The results showed that the drag of all riders in the peloton decreased compared to that of an isolated rider — but in the mid-rear section of the group, the reduction plunged to between 5 and 10 percent the drag of an isolated rider.

That’s up to 10 times less than previous assumptions, and it benefits almost half the cyclists in a peloton.

Read our case study to find out more about the Peloton Project.

Or watch this on-demand webinar featuring Cray, ANSYS, and special guest Professor Bert Blocken. You’ll hear about the largest CFD modeling ever done in sports, the challenges of properly meshing such an extreme geometry, and the impact of cycling aerodynamics on elite athletes.

The Peloton Project by the Numbers

  • 3 world-renowned universities (TU Eindhoven, KU Leuven and U Liège)
  • 2 leading global companies (ANSYS and Cray)
  • 3 model-building partners (Custom Company, FlexForm and Tenax)
  • 4 wind tunnel tests
  • 2 x 54 supercomputing hours
  • 13,824 parallel processes
  • More than 49,000 GB of memory

More About the Peloton Project

Comments

  1. 4

    neil chris vesce says

    It is great to see huge scale projects at work with Cray computer. Teamwork is vital with The Tour de France.
    What looked like a balloon in this years cycle peloton, from an areal view, did hold secrets. Congratulations on the new world record Cray!

  2. 5

    Bert Blocken says

    A VERY BIG thank you to the fantastic professionals at CRAY and ANSYS whose support has been essential for this study to be completed! It was a pleasure and a privilege to work with all of you.

  3. 6

    says

    Brilliant investigation, Interesting results, staggering amount of compute resources. Obvious implications for race car drivers. I wonder about fighter jet formations and thus also drone swarms for combat. I bet there may be some military money to earned for those studies !

  4. 7

    Thierry Marchal says

    Fantastic collaboration between CRAY, ANSYS, and the teams of Prof Bert Blocken at Technology University of Eindhoven and KU Leuven. Only world class partners closely working together could succeed with this amazing project.

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