The application of body scanning,numerical simulations and wind tunnel testing for the aerodynamic development of cyclists

Abstract

The aerodynamic efficiency of an elite cyclist is often evaluated and optimised using either one or a combination of field testing, wind-tunnel testing and numerical simulation. This study focuses on the processes and limitations involved in using a body scan to produce an accurate geometry for input to numerical simulation, with validation through drag comparisons from wind-tunnel tests and vortical wake-flow features reported in previous experimental studies. Transitional Shear Stress Transport Reynolds-Averaged Navier-Stokes simulations based on the scanned geometry were undertaken for a 180 ° half crank cycle at 15 ° increments. The sectional drag force contributions of 23 body subparts are presented, documenting the contribution and variation of each body/cycle component over the cycle. These methods are evaluated and the limitations of the approaches are discussed. The results from the numerical simulation and the wind tunnel measured drag force were very similar, differing by approximately 1%–7% for various crank angles.

Keywords

Cycling aerodynamics computational fluid dynamics sports performance drag scanning body scan

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References

Grappe

Candau

Belli

, et al. Aerodynamic drag in field cycling with special reference to the Obree position. Ergonomics 1997; 40(12): 1299–1311.

Kyle

Weaver

. Aerodynamics of human-powered vehicles. Proc IMechE, Part A: J Power and Energy 2004; 218(3): 141–154.

Kyle

Burke

. Improving the racing bicycle. Mech Eng 1984; 106(9): 34–45.

Griffith

Crouch

Thompson

, et al. Computational fluid dynamics study of the effect of leg position on cyclist aerodynamic drag. J Fluid Eng 2014; 136(10): 101105.

Underwood

. Aerodynamics of track cycling. PhD Thesis, Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand, pp.36–37, 2012.

Underwood

Jermy

. Fabric testing for cycling skinsuits. Procedia Eng 2011; 13: 350–356.

Defraeye

Blocken

Koninckx

, et al. Computational fluid dynamics analysis of cyclist aerodynamics: performance of different turbulence-modelling and boundary-layer modelling approaches. J Biomech 2010; 43(12): 2281–2287.

Blocken

van Druenen

Toparlar

, et al. Aerodynamic drag in cycling pelotons: new insights by CFD simulation and wind tunnel testing. J Wind Eng Indus Aerodyn 2018; 179: 319–337.

Blocken

Defraeye

Koninckx

, et al. CFD simulations of the aerodynamic drag of two drafting cyclists. Comput Fluid 2013; 71: 435–445.

10.

Crouch

Burton

Brown

NAT

, et al. Flow topology in the wake of a cyclist and its effect on aerodynamic drag. J Fluid Mech 2014; 748: 5–35.

11.

Barry

Burton

Sheridan

, et al. Aerodynamic drag interactions between cyclists in a team pursuit. Sport Eng 2015; 18(2): 93–103.

12.

Langtry

Menter

Likki

, et al. A correlation-based transition model using local variables II: test cases and industrial applications. J Turbomach 2006; 128(3): 423–434.

13.

Schmitt

. About Boussinesq’s turbulent viscosity hypothesis: historical remarks and a direct evaluation of its validity. Comptes Rendus Mécanique 2007; 335(9–10): 617–627.

14.

Shur

Spalart

Strelets

, et al. A hybrid RANS-LES approach with delayed-DES and wall-modelled LES capabilities. Int J Heat Fluid Flow 2008; 29(6): 1638–1649.

15.

Versteeg

Malalasekera

. An introduction to computational fluid dynamics: the finite-volume method. Pearson Education, 2007.

16.

Menter

Langtry

Likki

, et al. A correlation-based transition model using local variables I: model formulation. J Turbomach 2006; 128(3): 413–422.

17.

Seminati

Talamas

Young

, et al. Validity and reliability of a novel 3D scanner for assessment of the shape and volume of amputees’ residual limb models. PLoS ONE 2017; 12(9): e0184498.

18.

Michaeli

DeGroff

Roxas

. Error aggregation in the reengineering process from 3D scanning to printing. Scanning 2017; 2017: 1218541.

19.

Defraeye

Blocken

Koninckx

, et al. Aerodynamic study of different cyclist positions: CFD analysis and full-scale wind-tunnel tests. J Biomech 2010; 43(7): 1262–1268.

20.

Zdravkovich

. Flow around circular cylinders: Applications, vol. 2. Oxford: Oxford University Press, 1997.

21.

Crouch

. Flow topology and large-scale wake structures around elite low-drag cycling positions. PhD Thesis, Department of Mechanical Engineering and Aerospace Engineering, Monash University, Melbourne, VIC, Australia, pp.81–132, 2013.

22.

Blocken

Toparlar

. A following car influences cyclist drag: CFD simulations and wind tunnel measurements. J Wind Eng Indus Aerodyn 2015; 145: 178–186.

23.

Defraeye

Blocken

Koninckx

, et al. Computational fluid dynamics analysis of drag and convective heat transfer of individual body segments for different cyclist positions. J Biomech 2011; 44(9): 1695–1701.

24.

Defraeye

Blocken

Koninckx

, et al. Cyclist drag in team pursuit: influence of cyclist sequence, stature, and arm spacing. J Biomech Eng 2014; 136(1): 011005.

25.

Mannion

Toparlar

Clifford

, et al. On the effects of crosswinds in tandem aerodynamics: an experimental and computational study. European J Mech-B/Fluid 2019; 74: 68–80.