[Kuriosa] - CFDsimulering av luftmotstånd
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Några klipp.
"...By performing CFD simulations of a nine-man TTT, and a single cyclist ITT, it is possible to directly evaluate the influence of drafting...
The results of the simulations were illuminating. Compared with the lead cyclist, the drag of the rider in second place is reduced by 21% - a significant saving. The third rider feels a further small decrease in drag over the second, but from the third rider back all other cyclists experience almost identical drag. As the riders are continually progressing towards the front of the chain, taking a short turn on the front, before freewheeling to the rear of the line, on average (assuming a constant rate of rider rotation and ignoring the effect of dropping back) the drag coefficient of a rider in the TTT is around 27% lower than experienced by an individual rider.
Perhaps the most surprising conclusion from the CFD simulation is that, despite feeling the full force of the oncoming air, the lead rider experiences lower drag than if he were riding an ITT at the same speed. The drag coefficient of the leading TTT rider is 0.277, while that of an individual rider is 0.285 [drag coeffient is measure of the force each rider experiences corrected for differences in size]. This rare example of "something for nothing" occurs because the second place rider reduces the influence of the lead rider's wake, increasing his base pressure and consequently reducing the drag force that he experiences..."
http://www.cd-adapco.com/press_room/dynamics/25/tourdefrance.html
/Håkan
Några klipp.
"...By performing CFD simulations of a nine-man TTT, and a single cyclist ITT, it is possible to directly evaluate the influence of drafting...
The results of the simulations were illuminating. Compared with the lead cyclist, the drag of the rider in second place is reduced by 21% - a significant saving. The third rider feels a further small decrease in drag over the second, but from the third rider back all other cyclists experience almost identical drag. As the riders are continually progressing towards the front of the chain, taking a short turn on the front, before freewheeling to the rear of the line, on average (assuming a constant rate of rider rotation and ignoring the effect of dropping back) the drag coefficient of a rider in the TTT is around 27% lower than experienced by an individual rider.
Perhaps the most surprising conclusion from the CFD simulation is that, despite feeling the full force of the oncoming air, the lead rider experiences lower drag than if he were riding an ITT at the same speed. The drag coefficient of the leading TTT rider is 0.277, while that of an individual rider is 0.285 [drag coeffient is measure of the force each rider experiences corrected for differences in size]. This rare example of "something for nothing" occurs because the second place rider reduces the influence of the lead rider's wake, increasing his base pressure and consequently reducing the drag force that he experiences..."
http://www.cd-adapco.com/press_room/dynamics/25/tourdefrance.html
/Håkan
