Quote:
Originally Posted by aerohead
Member AeroStealth owns a 2014 Ford F-150 Eco-Boost, Crew Cab, 6.5-foot bed,4X4 pickup.
Ford Motor Company published Cd 0.404 for this pickup.
AeroStealth purchased member Bondo's ( Brett Herndon ) Aerolid and Aerotail, both wind tunnel tested, courtesy of the Ford Motor Company.
With the two modifications, the F-150 was reduced to Cd 0.306. A 24.25% drag reduction.
While Ford Motor has never published an official drag coefficient for the current F-150, it seems unlikely that it's drag coefficient has 'increased' by 14.6% since 2014.
In his Master's Thesis of 2011 at Chalmers University, Martin Olsson reported that the Lattice Boltzmann Method ( LBM ) CFD used, produced a 13% discrepancy between wind tunnel tests of the same model.
Does AirShaper employ LMB?
|
Hi Aerohead,
no, we use a finite volume method:
this has been the default method for decades, although I do believe LBM could be (one of) the winning methods for the future.
Regarding drag values:
without discrediting the manufacurers, the claimed values are usually fairly optimistic (as they sometimes play with ride heights, rims, aircon settings, etc during testing).
We performed an independent validation on a Tesla Model Y together with one of our partners - our Cd value was less than 6% off compared to the measured value. And qualitative data (the flow structure behind the car) also showed good correlation:
airshaper.com/blog/tesla-model-y-aerodynamic-benchmarking
I would agree drag hasn't increased by 14%, so it's likely more a matter of comparing the right data here. Data coming from different sources and/or different measuring techniques (tunnel vs simulation) can blur the whole story.