A bobsleigh race consists of two distinct phases. The first is the push phase, during which the athletes push the sled over a short distance to achieve maximum initial speed. This phase lasts about 7 seconds, during which the sled covers 40 meters and reaches a speed of approximately 30 km/h. The second phase is the descent, which lasts around 60 seconds over a distance of 1500 meters, with speeds reaching up to 130 km/h.
My research focused on this second phase, with particular attention to the women’s monobob, a new discipline introduced at the 2022 Winter Olympic Games. It was conducted during my internship at LAHDYX (Laboratory of Hydrodynamics of École Polytechnique), as part of Samy Ben Hamoudi's doctoral research on bobsleigh, under the supervision of Christophe Clanet.
The first part of this work involved the development of a "digital wind tunnel" to predict the drag and lift forces acting on the bobsleigh. To this end, a series of measurements was carried out in June 2024 in the S4 wind tunnel at the Institut Aérotechnique, along with a 3D scan of the sleds. I processed the experimental data and the scans, then developed a CFD model in OpenFOAM using a turbulence model of the "Spalart-Allmaras Delayed Detached Eddy Simulation" type, after testing different parameters and models.
The final parameters successfully reproduce the aerodynamic behavior of a monobob within the range of speeds observed on the track. This simulation can thus be used to optimize the athlete's position in the bobsleigh, the shape of their helmet, and the optimal trajectory of the bobsleigh on the track.
The second part of my work focused on the analysis of the bobsleigh track in La Plagne, France. This track, 1500 meters long with a total vertical drop of 200 meters, features 19 turns with varying radii and inclinations, making it a complex environment for trajectory optimization. It will be used during the 2030 Winter Olympic Games.
To accurately model the geometry of the track, a 3D scan was carried out by the National Institute of Geographic and Forest Information (IGN) using photogrammetry techniques. By cross-referencing this geometric data with measurements collected during the 2022 World Cup, I was able to reconstruct the actual trajectory followed by the bobsleighs.
This reconstruction, combined with the previously developed digital wind tunnel, provides a solid foundation for studying optimal trajectories. It will allow for a detailed analysis of aerodynamic interactions between the bobsleigh and the track, particularly identifying critical sectors where performance gains can be achieved through better control of the trajectory and the dynamics of the vehicle.
[Back to Homepage]List of publications
- Aerodynamics of bobsleighs, zenodo (2024), Maxime C.N. Roux, (DOI)
List of talks
- Sport Physics 2024, Rennes, December 2024 : Aerodynamics of bobsleighs: wind tunnel and CFD results, Maxime C.N. Roux, Samy Ben Hamoudi and Christophe Clanet, (abstract), (slides)