CFD of 2021 F1 Car

Here are our CFD links and discussions about aerodynamics, suspension, driver safety and tyres. Please stick to F1 on this forum.
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humble sabot
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Joined: Sat Feb 17, 2007 9:33 am

Re: CFD of 2021 F1 Car

Post Tue Jan 07, 2020 10:57 pm

godlameroso wrote:
Sun Dec 22, 2019 3:04 pm
CAEdevice wrote:
Sat Dec 21, 2019 10:39 pm
I am simulating a car (not a F1, it is nearer to a F3) with a F1 2021 floor layout: I am pretty sure (as you wrote on the article) that the optimum rake will be around 0°, no matter if the front wing will be (a bit) more distant from the ground. You will have a significant drag reduction and you don't have a diffuser peak to balance.
Perhaps a little bit of rake will be needed just for balance, the shift in rake at speed may also have very interesting effects on that balance. Particularly roll, and pitch.

What if more, not less body roll and pitch is favorable to the 2021 generation of aero rules. It would certainly force drivers to adapt a new style of driving, pitching and rolling the cars to set up for corners.

Very light brake application on corner entry to get the front end to turn in, and having to semi inertial drift the turns to get the most of the aero platform.
If you're suggesting that the floor is so easily stallable, I'd suggest that they would be more likely to err on the side of a firmer platform.
Current gen cars actually have a fair bit of compliance through corners compared to most other race cars, particularly at the rear, and it's the floor heigh that allows that to work as well as it does.
That being said I would subsequently expect that exploiting this floor format to its maximum will see some new kinds of out of the box thinking as most high budget series have not been playing around with full floor tunnels.
the four immutable forces:
static balance
dynamic balance
static imbalance
dynamic imbalance

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godlameroso
358
Joined: Sat Jan 16, 2010 8:27 pm
Location: Miami FL

Re: CFD of 2021 F1 Car

Post Tue Jan 07, 2020 11:09 pm

humble sabot wrote:
Tue Jan 07, 2020 10:57 pm
godlameroso wrote:
Sun Dec 22, 2019 3:04 pm
CAEdevice wrote:
Sat Dec 21, 2019 10:39 pm
I am simulating a car (not a F1, it is nearer to a F3) with a F1 2021 floor layout: I am pretty sure (as you wrote on the article) that the optimum rake will be around 0°, no matter if the front wing will be (a bit) more distant from the ground. You will have a significant drag reduction and you don't have a diffuser peak to balance.
Perhaps a little bit of rake will be needed just for balance, the shift in rake at speed may also have very interesting effects on that balance. Particularly roll, and pitch.

What if more, not less body roll and pitch is favorable to the 2021 generation of aero rules. It would certainly force drivers to adapt a new style of driving, pitching and rolling the cars to set up for corners.

Very light brake application on corner entry to get the front end to turn in, and having to semi inertial drift the turns to get the most of the aero platform.
If you're suggesting that the floor is so easily stallable, I'd suggest that they would be more likely to err on the side of a firmer platform.
Current gen cars actually have a fair bit of compliance through corners compared to most other race cars, particularly at the rear, and it's the floor heigh that allows that to work as well as it does.
That being said I would subsequently expect that exploiting this floor format to its maximum will see some new kinds of out of the box thinking as most high budget series have not been playing around with full floor tunnels.
The stalling is mostly from the way the front of the car deals with airflow, however diffuser performance will increase the closer it is to the ground up to a point.
The height of cultivation is really nothing special. It is merely simplicity; the ability to express the utmost with the minimum. Mr.Lee

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maunde
1
Joined: Sat Nov 02, 2019 11:36 am

Re: CFD of 2021 F1 Car

Post Fri Jan 10, 2020 5:29 am

Vyssion wrote:
Tue Dec 17, 2019 1:38 pm
G'day! It's been a while... hasn't it? :)

With the 2019 season now concluded, and jjn and I being in stage 4 withdrawals right now, we figured that we needed "something" to keep our mi... ooooooo!! Is that the 2021 regulations??? :lol:

So, without further ado, I would like to present to you all our first, and legal (to the best of our knowledge), 2021 spec. F1 car!! And the first car that is wholly of F1T design!!

-sigh-... who would have thought that Aerosaruman and Aerogandalf would ever work together again, huh? =D>

https://imgur.com/PYnaTVH.png
https://imgur.com/guOyb4N.png
https://imgur.com/IeQhAHn.png


So.......

What forum post from Vyssion would be complete, without some CFD: COLOUR FOR DIRECTORS!!

Very similar setup to the Perrinn model; straight ahead solve here, no crossflow or curved flow, steady-RANS w/ SST turbulence inc. wall functions, 31.5million elements, etc etc...


https://imgur.com/P6ED0ny.png
https://imgur.com/5R58Ahv.png
https://imgur.com/ThzSwAg.png


Here is a list of bullet points that, so far, we have twigged, and are gonna work on next. Now I am gonna shamelessly make excuses for any "iffy" performance or flow features you see, because... IT WAS OUR FIRST GO AT IT, OKAYYYY?? :cry: Overall, for a first go at it, the car performs very, very well; hats off to jjn.
  • CzS = -4.95
  • CxS = 1.80
  • Front Wheel wake is pretty crazy now... we will work on this
  • Going to reduce pitch setting of FW flaps
  • Inboard floor fence vortex isnt under control (just spreads out)
  • 2021 Force Breakdown = Floor (50%), FW (37%), RW (25%)
  • Compared to Perrinn = Floor (55%), FW (30%), RW (40%)
  • Higher than 100% is due to Lift generated on the chassis and wheels (6% lift on 2021 wheels, 9% lift on Perrinn)
  • Balance of 2021 is ~49% which is quite far forward, so we will correct this (starting with FW flaps as mentioned above)
  • Surprisingly large amount of low pressure below the car
  • Front suspension is stalled
  • Top of floor inlet is stalled
  • Rear of Lower sidepod expansion has stalled
  • RW flap stalled in curved EP sections (and slightly along TE) and RW as a whole is very draggy
-edit- replaced old gifs with larger ones - I made a mistake when I was creating them... oopsies
https://imgur.com/s0WIUwj.gif
https://imgur.com/rUTxoyq.gif
https://imgur.com/KYFQvuG.gif
https://imgur.com/2faOvGm.png
https://imgur.com/1wXjL5V.png
https://imgur.com/zTHRlNz.png
https://imgur.com/zueL8hT.png
https://imgur.com/bBaIjl3.png
https://imgur.com/9fPR6mf.png
https://imgur.com/kLcnClK.png
Hey Vyssion,

Would you be able to talk more about the rear-wheel fence/strake-like/vane features adjacent to the rear wheels? What are your thoughts on the expected interactions between these vanes and the diffuser? My assumption is that this could be used to control the rear-wheel tyre squirt as well as aid the diffuser (preventing in-flow).

Did you notice any interesting flow regimes in this area?

Thanks for the feedback!
A kiwi looking to fly like McLaren.

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jjn9128
254
Joined: Tue May 02, 2017 10:53 pm

Re: CFD of 2021 F1 Car

Post Fri Jan 10, 2020 1:08 pm

Those fences/vanes are spec parts. Though there is leeway for a small angle so the teams can play with it to adjust to their individual flow fields.

As they're not fully detailed in the regs I had to make them up from the little information available and the pics of the wind tunnel model. I feel we've recreated the purpose if not the exact geometry. Same goes with the front arch winglets!

The purpose is to stop the tyre squirt entering the diffuser. The bigger Venturi/diffusers draw a huge volume of air from the sides into the end-fence vortical structures, so stopping "low energy" stuff like the tyre wake getting in is important.

They do the job pretty well if you look at the gif. The tyre squirt doesn't mix with the diffuser flow until behind the car. So is not directly affecting the downforce generating surface.
#aerogandalf

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maunde
1
Joined: Sat Nov 02, 2019 11:36 am

Re: CFD of 2021 F1 Car

Post Fri Jan 10, 2020 1:31 pm

jjn9128 wrote:
Fri Jan 10, 2020 1:08 pm
Those fences/vanes are spec parts. Though there is leeway for a small angle so the teams can play with it to adjust to their individual flow fields.

As they're not fully detailed in the regs I had to make them up from the little information available and the pics of the wind tunnel model. I feel we've recreated the purpose if not the exact geometry. Same goes with the front arch winglets!

The purpose is to stop the tyre squirt entering the diffuser. The bigger Venturi/diffusers draw a huge volume of air from the sides into the end-fence vortical structures, so stopping "low energy" stuff like the tyre wake getting in is important.

They do the job pretty well if you look at the gif. The tyre squirt doesn't mix with the diffuser flow until behind the car. So is not directly affecting the downforce generating surface.
Thanks for the reply.

That's quite disappointing they are spec parts - it would have been an interesting part to optimize. Ofcourse this area of freedom doesn't necessarily help the intention of the new regs.

How would you differentiate between the characteristics of the tyre squirt vortex and the vortex generated by a vortex generator used for downforce generation (the front underbody vanes, for example)? Can the tyre squirt vortices be used for downforce generation?

Cheers
A kiwi looking to fly like McLaren.

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jjn9128
254
Joined: Tue May 02, 2017 10:53 pm

Re: CFD of 2021 F1 Car

Post Fri Jan 10, 2020 1:48 pm

How interesting it would be to develop would depend on how tight of free the rules are. Sadly I don't see a huge amount of interest in developing parts for the 2021 rules as they're incredibly prescribed.

The function of vortex generators must be seen in relation to scale. So a small vortex generator on a wing or diffuser surface will influence the surface at boundary layer scale i.e they're boundary layer turbulators. The point being to shift the stall condition. So more camber/incidence/lower ground clearance increasing pressure gradient.

Larger vortices have larger effects so aren't useful for that boundary later scale. Mostly they're from geometries aimed at turning the flow but the core can infer a pressure on a surface. Under ground effect the vortex core generally remains fixed as it progresses in a stream wise direction.

Tyre squirt is tricky to control. The size of the vortex isn't static. Changes to the sidewall compression or camber (mid corner a negative static camber can become positive depending on roll stiffness) can have large effects on the size and position of the vortex. This is part of the reason for 18" wheels. Certainly why I suggested it to FOM. Though I think they've somewhat counteracted that by increasing the diameter to 725mm.
#aerogandalf

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maunde
1
Joined: Sat Nov 02, 2019 11:36 am

Re: CFD of 2021 F1 Car

Post Fri Jan 10, 2020 2:13 pm

jjn9128 wrote:
Fri Jan 10, 2020 1:48 pm
How interesting it would be to develop would depend on how tight of free the rules are. Sadly I don't see a huge amount of interest in developing parts for the 2021 rules as they're incredibly prescribed.

The function of vortex generators must be seen in relation to scale. So a small vortex generator on a wing or diffuser surface will influence the surface at boundary layer scale i.e they're boundary layer turbulators. The point being to shift the stall condition. So more camber/incidence/lower ground clearance increasing pressure gradient.

Larger vortices have larger effects so aren't useful for that boundary later scale. Mostly they're from geometries aimed at turning the flow but the core can infer a pressure on a surface. Under ground effect the vortex core generally remains fixed as it progresses in a stream wise direction.

Tyre squirt is tricky to control. The size of the vortex isn't static. Changes to the sidewall compression or camber (mid corner a negative static camber can become positive depending on roll stiffness) can have large effects on the size and position of the vortex. This is part of the reason for 18" wheels. Certainly why I suggested it to FOM. Though I think they've somewhat counteracted that by increasing the diameter to 725mm.
You are insightful as always!

This all makes sense. How often are larger scale generators used solely for vortex generated downforce? Without much regard for actually turning the flow? I am aware that this would depend on the availability of ground affect, but would like to know your thoughts on the topic.

Cheers
A kiwi looking to fly like McLaren.

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jjn9128
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Joined: Tue May 02, 2017 10:53 pm

Re: CFD of 2021 F1 Car

Post Fri Jan 10, 2020 2:31 pm

Generating the vortex requires some form of cambered surface and the downforce you get from the core isn't that big compared to the drag you produce to create it anyway, probably closer to 1:1 than say a T wing which will be of the order of 10-15:1. As a side effect or secondary effect it can be beneficial as a main aim it's generally not worthwhile. I say generally because there are exceptions where the downforce is essential regardless of how dirty or cases where the drag will offset elsewhere.

An example would be the vanes in modern diffusers. They're not fences of multi channel in the tradition sense.
#aerogandalf

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JordanMugen
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Joined: Wed Oct 17, 2018 12:36 pm

Re: CFD of 2021 F1 Car

Post Sun Jan 12, 2020 6:19 pm

maunde wrote:
Fri Jan 10, 2020 1:31 pm
Can the tyre squirt vortices be used for downforce generation?

Cheers
Isn't that what the Valkyrie diffuser design is for? To bring in the tyre squirt to contribute to the diffuser counter rotating vortex pair.

Image

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godlameroso
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Joined: Sat Jan 16, 2010 8:27 pm
Location: Miami FL

Re: CFD of 2021 F1 Car

Post Mon Jan 20, 2020 5:11 pm

What I have noticed is that the rear end of the car will be the biggest area teams can improve on. Meaning the best and tightest packaging of the chassis will have the best aero performance. This is still something that favors the big teams, if you look at the packaging of the rear end of the Mercedes vs an Alfa Romeo you can see just how much more sculpted and aggressive the Mercedes design is.

That level takes a lot of engineering and development to improve. It is a very costly area to develop as the parts must be over engineered to last. These parts include the transmission, the radiator layout, the fuel tank, survival cell. All of these things affect the engine installation which affects the balance of the chassis as well as aero performance.
The height of cultivation is really nothing special. It is merely simplicity; the ability to express the utmost with the minimum. Mr.Lee