Quote:
Originally Posted by California98Civic
Test me.
What I see in post #219 and third image in post #216 is the smoke loosing all definition in the flow, becoming one hazy cloud adjacent to the body. In post 219, I'm assuming this effect reflects the higher pressures at the front of the roof that then drop as we move aft. And in the thrid image in post 216 it might be a similar presure effect compounded by the turbulence created by the front wheel well.
Assuming I'm in the general ballpark of understanding these images, post 219's image, which seems to be unusually close to the template ideal at the front end and along the roof line, suggests strongly the limits of front end aero. Won't the wake on this body be quite large without boat tailing?
Also, the third image in post 216 suggests that a skirt on the rear wheel wells will have much less benefit without front wheel well skirts, yes? Expect turbulence.
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This is complicated without a plan-view of the boxfish.
*The high pressure will occur right in front of the grille.
*The highest velocity pressure (lowest static pressure) will occur just ahead of the windshield header/A-pillars.
*As the flow moves behind the line of maximum body crossection,the velocity pressure will begin to fall off as the static pressure begins to build,in compliance with the Bournoulli Theorem.
*As the flow breaks away at the rear,it is as slow as it's going to get at this body length,and its pressure the highest,leading to a higher static pressure in the wake,or base drag.
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*If you analyze the Boxfish in side elevation only,the Aerodynamic Streamlining Template would predict only Cd 0.255 for Boxfish.
*However,Mercedes-Benz has moved the side body camber to a forward bias,beginning the plan-view boat-tailing before the side elevation boat-tailing.
*From the side,Boxfish's forebody = 52% of total body length,with 48% aft-body.
*She has a Length/Height ratio of 2.56.
*We have no exact data about her plan-view.
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In comparison,FIAT constructed a 'boxfish-like' test model in 1986,with only L/D= 2.347 and achieved Cd 0.17.
*In side elevation the forebody= 60% body length,aft-body= 40%.
*In plan-view,forebody= 40%,aft-body= 60%.
*Fiat moved the side body camber maximum point from between the wheelbase,to the rear of the front tire,beginning the plan taper forward,as the Schl'o'rwagen of the 1930s.
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With the forward-biased plan taper,the wake region is deceptively narrow compared to the body height,leading to a smaller than expected wake.
*Renault's 1987 Vesta II was constructed the same way,achieving Cd 0.19 with a remarkably short car.
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Without accurate plan views it's very difficult to understand airflow across a car.
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