新闻中心

New research may lead to a different strategy of cycling teams in escape attempts

作者:Elsevier

时间 :2018/7/11 0:00:00

Amsterdam, July 11, 2018 - In the middle of a peloton, racing cyclists experience only five to ten percent of the air resistance they face when cycling alone. A new study, published in the Journal of Wind Engineering & Industrial Aerodynamics, based on wind tunnel research on a peloton of 121 cyclists may explain why so few 'breakaways' in professional cycling races, like this year's Tour de France, are successful.

"It turns out that current calculation models used by some race teams to determine the best time to escape are based on the wrong assumptions," explains lead author Professor Bert Blocken at the Eindhoven University of Technology & KU Leuven. "Perhaps these new results will lead to more successful escapes and partly explain why so few escapes succeed, and why the peloton often hauls in the riders that do escape," Dr. Blocken added.

It is well known that in the middle of a cycling peloton you ride 'out of the wind' and therefore experience less air resistance. How much less has never been thoroughly investigated. From previous research with smaller groups of riders, estimates have been made of 50 to 70 percent of the air resistance is experienced when compared to individual riders. Professional cyclists however, suggest that in a peloton you 'sometimes hardly have to pedal', which assumes that air resistance must be much lower.

The research team, led by Dr. Blocken systematically chart, for the first time, the air resistance for each rider in a cycling peloton of 121 riders. The results showed that in the middle and at the back of the peloton the drag is about five to seven percent of what is experienced by a single rider. "Put it another way: it is as if a rider is cycling at 12 to 15 km/h in a peloton that is speeding along at 54 km/h," Dr. Blocken added. "That's why it feels like riders expend so little energy at the back." Riders can now use these data to see what the best place is in a peloton.

But Dr. Blocken warned that "this does not mean a recreational cyclist can cycle along with the professional peloton. This might be possible for a short distance with a straight road on flat terrain, but as soon as bends are taken, the accordion effect sets in, and the peloton stretches out, causing the resistance to become much higher."

The study is a combination of computer simulations and wind tunnel measurements (including a complete peloton of 121 models), which independently gave the same results. Researchers examined two pelotons of 121 riders, where the distance between the rows differed slightly. Computer simulations amounted to 3 billion cells - a world record for a sports application - and required CRAY's American supercomputers and tens of thousands of software licenses from the company ANSYS. Simulations had to run for 54 hours for the calculation of a peloton, with a total of 49 terabytes of working memory.

"At the very back, the air resistance is very low, but there is less opportunity to react to attacks and chances increase greatly for getting caught in a crash," says Dr. Blocken. "So for classification riders or sprinters, the best position is in row six, seven or eight: there you are sufficiently shielded by other riders and you're near enough to the front."

The study also considered a peloton with a regular arrangement of riders, in order to allow clear conclusions to be drawn. The cyclists were static, not pedaling and not moving from one position to another in the peloton. There was no strong head-, tail- or side-wind. Only aerodynamic resistance was considered. The effects of these limitations will be investigated in follow-up studies by the researchers.

###

Notes for editors

The article is "Aerodynamic drag in cycling pelotons: New insights by CFD simulation and wind tunnel testing," by Bert Blocken et al. (https://doi.org/10.1016/j.jweia.2018.06.011). It appeared in Journal of Wind Engineering and Industrial Aerodynamics, volume 179 (August, 2018), published by Elsevier.

This study is published open access and can be downloaded by following the DOI link above.

Journalists wishing to interview the authors may contact Bert Blocken at b.j.e.blocken@tue.nl or +31 6 482 410 29.

About Journal of Wind Engineering & Industrial Aerodynamics

The Journal of Wind Engineering & Industrial Aerodynamics' objective is to provide a means for the publication and interchange of information, on an international basis, on all those aspects of wind engineering that are included in the activities of the International Association for Wind Engineering. These are: social and economic impact of wind effects; wind characteristics and structure, local wind environments, wind loads and structural response, diffusion, pollutant dispersion and matter transport, wind effects on building heat loss and ventilation, wind effects on transport systems, wind power generation, and codification of wind effects.

About Elsevier

Elsevier is a global information analytics business that helps institutions and professionals advance healthcare, open science and improve performance for the benefit of humanity. Elsevier provides digital solutions and tools in the areas of strategic research management, R&D performance, clinical decision support and professional education, including ScienceDirect, Scopus, SciVal, ClinicalKey and Sherpath. Elsevier publishes over 2,500 digitized journals, including The Lancet and Cell, 38,000 e-book titles and many iconic reference works, including Gray's Anatomy. Elsevier is part of RELX Group, a global provider of information and analytics for professionals and business customers across industries. http://www.elsevier.com

Media contact

Jonathan Davis, Communications Officer
Elsevier
+31 20 485 2719
j.davis.1@elsevier.com

<< 上一篇:UTA researcher to increase efficiency, reliability, security of national power grid 下一篇:Why are neuron axons long and spindly? Study shows they're optimizing signaling efficiency>>
技术支持:北京华宇星航国际教育科技有限公司 京ICP备18034610号

人工智能在线咨询

智能在线咨询 X

关于我们

该服务平台支持关键词检索、文献题名检索(准确题名)、文献DOI号检索、作者检索。当查询题名返回的结果无法下载全文数据或查询不到时,请找到所查文献DOI号后再次查询。查询结果会在10秒内返回, 24小时不间断的提供文献查询服务。

微信端

人工智能在线咨询