On the aerodynamic flow around a cyclist model at the hoods position

Miau, Jiun‐Jih; Li, Shang Ru; Tsai, Z. X.; Mai, Van-Phung; Lin, Shih-Chin

doi:10.1007/s12650-019-00604-2

Cited by 9 publications

(8 citation statements)

References 26 publications

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“…This appearance is associated with two large-scale counter-rotating vortical flows induced by flow separation from the shoulders and the upper body, subsequently re-attached at the center of the back surface. For reference, a numerical plot of the streamline distribution in Figure 10(b) (Miau et al, 2020) for a cyclist model at the hoods position illustrates the formation of the vortical flows over the back surface. This flow characteristic was also mentioned in Crouch et al (2014) and Crouch et al (2017) for models at different postures.…”

Section: Results Of the Water-channel Experimentsmentioning

confidence: 99%

“…From the perspectives of fluid dynamics, a cyclist can be regarded as a three-dimensional bluff body, from which flow gets separated and developed into a wake region downstream (Crouch et al, 2014(Crouch et al, , 2016a(Crouch et al, , 2016b(Crouch et al, , 2017Miau et al, 2020). According to a flow visualization experiment made in a water channel with a 1/5 scale cyclist model, Miau et al (2020) pointed out that the limiting streamline pattern (Lighthill, 1963) on the surface provided valuable information concerning the development of three-dimensional flow separation from the model. Miau et al (2020) further commented that delaying the flow separation would lead to reduction of the aerodynamic drag and suppression of the wake region behind the cyclist model.…”

Section: Introductionmentioning

confidence: 99%

“…According to a flow visualization experiment made in a water channel with a 1/5 scale cyclist model, Miau et al (2020) pointed out that the limiting streamline pattern (Lighthill, 1963) on the surface provided valuable information concerning the development of three-dimensional flow separation from the model. Miau et al (2020) further commented that delaying the flow separation would lead to reduction of the aerodynamic drag and suppression of the wake region behind the cyclist model.…”

Section: Introductionmentioning

confidence: 99%

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A study of drag reduction with textile roughness on a cyclist model

Hsu

Miau

et al. 2021

The Journal of The Textile Institute

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Efforts were made to examine the effect of textile roughness for the reduction of aerodynamic drag experienced on a cyclist model. First of all, flow visualization experiments were conducted in a water channel with a 1/5 scale cyclist model to identify the flow separation lines on the contoured surface. Subsequently, based on the information learned, the idea of delaying flow separation on the model surface was implemented by means of sport suits. Seven sport suits featuring different textile materials and local roughness patterns were tested on a full-scale cyclist model in wind tunnel experiments, in addition to a reference case without a sport suit. From the C D data deduced, we identified a critical condition in most of the cases studied, featuring a least drag coefficient occurred at a Reynolds number within the flow speed range studied. For the best case found, the drag coefficient is amounted 7.5% less than that of the reference case at the same Reynolds number. Furthermore, the C p and C prms values reduced from the pressure measurements on the cyclist model with the sport suits unveil a trend that the reduction of drag actually infers the retreat of the local flow separation lines toward the rear side of the body accompanied with less severe the flow unsteadiness.

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Section: Results Of the Water-channel Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A study of drag reduction with textile roughness on a cyclist model

Hsu

Miau

et al. 2021

The Journal of The Textile Institute

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“…In track sports where an average speed of approximately 60 km/h and a maximum speed of over 70 km/h exist, development of aerodynamically superior clothing is a crucial factor to convert the energy into propulsion efficiently. For this reason, the airflow around cyclists and the slipstream have been analyzed, in detail, in previous studies [6][7][8][9][10], while others have focused on methods to evaluate the air resistance acting on bicycles [11]. Lately, researchers have investigated the airflow to the wheels using computational fluid dynamics (CFD) [12], while others have focused on the effect of the posture of a cyclist on the drag and airflow [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Aerodynamics of Cycling Skinsuits Focused on the Surface Shape of the Arms

Hong

Asai

2021

Applied Sciences

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In cycling, air resistance corresponds to 90% of the resistance on the bicycle and cyclist and 70% of this is applied to the body of the cyclist. Despite research on postures that could reduce air resistance, few studies have been conducted on full-body cycling suits. As the aerodynamics of the surface shape of clothing fabric are still unclear, the airflow around cyclists and air resistance were examined using a computational fluid dynamics (CFD) method and wind tunnel experiment. Specifically, in this study, we focused on how different surface shapes of cycling suit fabrics affect air resistance. CFD results indicate that air resistance during a race was high at the head, arms and legs of the cyclist. In the wind tunnel experiment, a cylinder model resembling the arms was used to compare the aerodynamic forces of various fabrics and the results showed that air resistance changed according to the fabric surface shape. Moreover, by changing the fabric shape of the arms of the cycling suits, reduction of air resistance by up to 8% is achievable. These results suggest that offering the most appropriate suit type to each cyclist, considering race conditions, can contribute to further improvement in their performance.

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“…Recently, some researchers have been using different mannequins to assess drag force [20]. Thus, single mannequin to perform the numerical simulations allow to compare edited mannequins/models [20][21][22][23]. Upon that, data about energy cost may help coaches, cyclists and sports analysts to control cyclist's performance [15].…”

Section: Introductionmentioning

confidence: 99%

The Aerodynamics and Energy Cost Assessment of an Able-Bodied Cyclist and Amputated Models by Computer Fluid Dynamics

Forte

Marinho

Silveira³

et al. 2020

Medicina

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Background and Objectives: The aim of this study was to assess and compare the drag and energy cost of three cyclists assessed by computational fluid dynamics (CFD) and analytical procedures. Materials and methods: A transradial (Tr) and transtibial (Tt) were compared to a full-body cyclist at different speeds. An elite male cyclist with 65 kg of mass and 1.72 m of height volunteered for this research with his competition cloths, helmet and bicycle with 5 kg of mass. A 3D model of the bicycle and cyclist in the upright position was obtained for numerical simulations. Upon that, two more models were created, simulating elbow and knee-disarticulated athletes. Numerical simulations by computational fluid dynamics and analytical procedures were computed to assess drag and energy cost, respectively. Results: One-Way ANOVA presented no significant differences between cyclists for drag (F = 0.041; p = 0.960; η2 = 0.002) and energy cost (F = 0.42; p = 0.908; η2 = 0.002). Linear regression presented a very high adjustment for absolute drag values between able-bodied and Tr (R2 = 1.000; Ra2 = 1.000; SEE = 0.200) and Tt (R2 = 1.00; Ra2 = 1.000; SEE = 0.160). The linear regression for energy cost presented a very high adjustment for absolute values between able-bodied and Tr (R2 = 1.000; Ra2 = 1.000; SEE = 0.570) and Tt (R2 = 1.00; Ra2 = 1.00; SEE = 0.778). Conclusions: This study suggests that drag and energy cost was lower in the able-bodied, followed by the Tr and Tt cyclists.

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On the aerodynamic flow around a cyclist model at the hoods position

Cited by 9 publications

References 26 publications

A study of drag reduction with textile roughness on a cyclist model

A study of drag reduction with textile roughness on a cyclist model

Aerodynamics of Cycling Skinsuits Focused on the Surface Shape of the Arms

The Aerodynamics and Energy Cost Assessment of an Able-Bodied Cyclist and Amputated Models by Computer Fluid Dynamics

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