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Old 03-14-2020, 04:20 PM   #1 (permalink)
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Cybertruck CFD:INVERSE rebuttal

Inverse.com offers a rebuttal to Engines and Boats CFD analysis of Cybertruck,criticizing elements of the presentation already volunteered and discussed by Engines and Boats.Wouter Remmerie concludes that Cybertruck will offer Cd 0.48,and Infographics offers Cd 0.47.
The piece is worth a read.

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Old 03-15-2020, 05:14 PM   #2 (permalink)
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Inverse.com is a click-hole with no search. DDG can't find your article.

I'll have to take your word.
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Old 03-18-2020, 12:40 PM   #3 (permalink)
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Originally Posted by freebeard View Post
Inverse.com is a click-hole with no search. DDG can't find your article.

I'll have to take your word.
I had just GOOGLED 'Cybertruck computational fluid dynamics' and it was one of the first things that came up.Same for the others.
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Old 03-18-2020, 04:08 PM   #4 (permalink)
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Wouter Remmerie

I tracked down Wouter Remmerie online.He's the creator of AirShaper.com virtual wind tunnel.At his website,you can find his analysis of Cybertruck which he describes as a ' quick and dirty analysis based on a public 3D model.'
Some comments on the model:
*actual forebody side elevation curvature is absent.
*Actual aft-body upper curvature is absent.
*Actual 5-facet plan-view camber and boat-tailing is absent.
*Potential in-operation body ground clearance,or inclination (rake) cannot be known ahead of time.
Also,zero-yaw,or SAE,crosswind averaged coefficient of aerodynamic drag is not addressed.
--------------------------------------------------------------------------
Comments:
Any prediction of Cd 0.48 would be predicated upon vortex drag.From the vortex research of Ahmed,Baumert,Bearman,Davis,Howell,Hucho,Janssen,J ones,and Morel,it would be problematic to generate Cd 0.48 from a prismatic fastback model,given the particular architecture of Cybertruck.
From the Ahmed body,it's been demonstrated that vortex drag cannot be supported given consideration of diffuser angle, boat-tailing,and chamfer,all features incorporated into Cybertruck,especially with its active air-suspension.Tumblehome,also a feature of Cybertruck,is not considered at all in the prismatic model studies,and tumblehome is critical to drag optimization of the fastback form.
Oddly enough, the Ahmed body achieves its lowest drag with an identical Cybertruck backlight angle.Volkswagen also found it to be true for their Gen-I Golf/Rabbit.
Had these subtle features been incorporated into the CFD analysis,I suspect that the numbers generated,would take on an entirely different appearance.

Wind tunnel investigations of Nuccio Bertone concept car bodies of the late 60s,early 70s reveal zero forebody separation or edge vorticity with forms remarkably similar to Cybertruck.
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Old 03-18-2020, 04:12 PM   #5 (permalink)
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Quote:
At his website,you can find his analysis...
Someone should point out that the button is your friend.
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Old 03-18-2020, 04:19 PM   #6 (permalink)
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friend

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Originally Posted by freebeard View Post
Someone should point out that the button is your friend.
Years ago you helped walk me through linking.Once I lost Photobucket I kinda burned out and stopped trying.I agree that I should do it.Help?
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Old 03-18-2020, 05:39 PM   #7 (permalink)
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Happy to help, it's what I like to do.
  1. Acquire URL of target (copy from the box at the top left of most browser windows)
  2. In Message: text window click the button. It's left of and
  3. Paste into the entry field
  4. Profit!

Hope This Helps [HTH]
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Old 03-18-2020, 10:23 PM   #8 (permalink)
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Is this It?

https://www.linkedin.com/pulse/tesla...outer-remmerie
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Old 03-21-2020, 01:02 PM   #9 (permalink)
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It?

Quote:
Originally Posted by wdb View Post
Yes! Thanks.You'll want to click for the full report.
Based upon the 'simplicity' of the model,the Cd 0.48 that was generated must be taken within the context of what's omitted from the model's details.
If you add in the missing body curvature in side elevation,the missing forebody camber in plan view,the missing boat-tailing in plan view,and potential missing underbody inclination,there's a high probability that Cybertruck is incapable of producing any longitudinal vorticity,needed to create anything like Cd 0.48.
We know from investigations of Nuccio Bertone's Cybertruck-esque bodies of earlier,that the forebody is incapable of separated flow.The greenhouse flow is attached.The C-pillar/butresses have attached flow.Cybertruck's 'backlight' angle cannot produce vorticity for the reasons mentioned above.Cybertruck has the longest aftbody of any production vehicle,exceeding the Volkswagen XL1,Cd 0.189,and Volkswagen's research 'Flow' body,Cd 0.15.If you look at the cosine function of its attack and extractor jet geometry you'll find only very weak functions and intersections which have to be navigated by the turbulent boundary layer.Since streamlining is all about a vehicle's aft-body attached flow and minimum wake,low pressure drag,Cybertruck may demonstrate an industry-leading drag coefficient when the official numbers are finally published.The more I look at it,the more I marvel at what's hiding in plain view.

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