Mercedes W13

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101FlyingDutchman
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Joined: 27 Feb 2019, 12:01

Re: Mercedes W13

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tok-tokkie wrote:
15 Mar 2022, 09:55
I have only seen a few of the video clips linked on F1 Technical.
What has struck me is how close the Merc floor is to the road. It is just skimming the track in the vids I have seen.
The Red Bull, Ferrari (& McLaren?) are much further away.
There have been CFD shots showing the vortex running down the side of the floor forming a "skirt" to the floor &, hence, the tunnel.
In particular Red Bull has a wedge shaped vane creating a really strong vortex to provide this seal.
I suspect that Mercedes will adopt the same tactic to seal the floor. Then they need not run so close to the road. Then the choking problem will be resolved and the porpoising eliminated.
I actually wonder if they anticipated this all along (or certainly after Barcelona) and have the revised floor ready for the race.
I genuinely feel they will. Whenever I’ve seen Merc in testing Over the years they’ve ALWAYS explored the absolute limits of their testing envelope. I think it’s more to do with finding interesting development directions/set up windows for different track layouts etc.

Quite possibly what they are “concerned” about is the level of porpoising compared to their simulator/simulations which may perhaps indicate a small level of correlation issue. None of the team comms seem particularly perturbed as to the issue. I think it’s been a case of learning as much about the car as possible

izzy
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Joined: 26 May 2019, 22:28

Re: Mercedes W13

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tok-tokkie wrote:
15 Mar 2022, 09:55
I have only seen a few of the video clips linked on F1 Technical.
What has struck me is how close the Merc floor is to the road. It is just skimming the track in the vids I have seen.
The Red Bull, Ferrari (& McLaren?) are much further away.
There have been CFD shots showing the vortex running down the side of the floor forming a "skirt" to the floor &, hence, the tunnel.
In particular Red Bull has a wedge shaped vane creating a really strong vortex to provide this seal.
I suspect that Mercedes will adopt the same tactic to seal the floor. Then they need not run so close to the road. Then the choking problem will be resolved and the porpoising eliminated.
I actually wonder if they anticipated this all along (or certainly after Barcelona) and have the revised floor ready for the race.
As far as my fan-level understanding goes, the low pressure comes from the velocity of the air. So the sealing is good but other things being equal, with the aperture of the tunnels being constant then the smaller the gap to the road the higher the velocity will be when the air is forced into that space.

Until it gets too small and chokes of course. Choking is losing the velocity. But until then, the closer you are to the road, the more downforce you will have.

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ringo
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Re: Mercedes W13

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Vanja #66 wrote:
15 Mar 2022, 08:26
ringo wrote:
15 Mar 2022, 05:57
The road. You have the standing air over the ground. the floor of the car will exert a shear force on the air and shear it across the road. A shear force profile will develop between the floor and the road.
The road is very bumpy compared to the floor so i suspect turbulence.
It's an interesting thing to imagine, but its not the same as the text book boundary layer interacting with one surface.

compressible Couette flow
In the example of Couette flow you've given, there is no fluid movement on the stationary plate (i.e. road surface) so there is no boundary layer formation. This is well known.

https://i.ibb.co/p6qXG1n/640px-Laminar-shear-svg.png

Couette flow is not entirely comparable to floor going over the road, as Couette flow is stationary flow. And car racing is anything but stationary...

S E C T I O wrote:
15 Mar 2022, 07:24
Sorry if I ask you directly, but I see that beyond knowledge,you have kindness and patience, and sorry if it's a stupid question,i'm not a technic guy.Few years ago a type of swimsuit was unveiled,that reduced drag in the water so much that it was then banned. I thought it would be shortly before seeing similar concepts applied to the surfaces of an F1 to slow down / accelerate the flow in the various areas of the bodywork,where it is needed, but none of this has happened, is there a specific reason for this? Maybe the rules?Thanks if you would like to reply and still sorry for your time.
Never apologize for asking questions. :) It's the rules, yes, such surface treatment of F1 bodywork would consistute uneven surfaces which would go against the minimal bodywork radii rules. If a team would try to explain this as surface manufacturing imperfections, the pattern would clearly be visible and FIA woudn't accept this explanation. It's very likely one or more teams have tried doing this years ago, but the FIA stopped them right away.
No.The car is moving. relative motion. Road moving away from the car or car moving away from the road. whatever you want to choose.
And there is a boundary layer. always is.
From there is friction there is a boundary layer. It can never be zero.
For Sure!!

Just_a_fan
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Joined: 31 Jan 2010, 20:37

Re: Mercedes W13

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ringo wrote:
15 Mar 2022, 14:37
Vanja #66 wrote:
15 Mar 2022, 08:26
ringo wrote:
15 Mar 2022, 05:57
The road. You have the standing air over the ground. the floor of the car will exert a shear force on the air and shear it across the road. A shear force profile will develop between the floor and the road.
The road is very bumpy compared to the floor so i suspect turbulence.
It's an interesting thing to imagine, but its not the same as the text book boundary layer interacting with one surface.

compressible Couette flow
In the example of Couette flow you've given, there is no fluid movement on the stationary plate (i.e. road surface) so there is no boundary layer formation. This is well known.

https://i.ibb.co/p6qXG1n/640px-Laminar-shear-svg.png

Couette flow is not entirely comparable to floor going over the road, as Couette flow is stationary flow. And car racing is anything but stationary...

S E C T I O wrote:
15 Mar 2022, 07:24
Sorry if I ask you directly, but I see that beyond knowledge,you have kindness and patience, and sorry if it's a stupid question,i'm not a technic guy.Few years ago a type of swimsuit was unveiled,that reduced drag in the water so much that it was then banned. I thought it would be shortly before seeing similar concepts applied to the surfaces of an F1 to slow down / accelerate the flow in the various areas of the bodywork,where it is needed, but none of this has happened, is there a specific reason for this? Maybe the rules?Thanks if you would like to reply and still sorry for your time.
Never apologize for asking questions. :) It's the rules, yes, such surface treatment of F1 bodywork would consistute uneven surfaces which would go against the minimal bodywork radii rules. If a team would try to explain this as surface manufacturing imperfections, the pattern would clearly be visible and FIA woudn't accept this explanation. It's very likely one or more teams have tried doing this years ago, but the FIA stopped them right away.
No.The car is moving. relative motion. Road moving away from the car or car moving away from the road. whatever you want to choose.
And there is a boundary layer. always is.
From there is friction there is a boundary layer. It can never be zero.
Until the car gets there, the air is basically still and sat next to the road surface - yes, there are currents caused by thermal movement and wind, but they are essentially random and pretty small velocity compared to the car. The car then moves over the road surface and the layer of air. The air will start to move because of the car's boundary layer, etc., and by the time it's started to make an appreciable boundary layer with the road surface, the car has gone. The air's interaction with the road is essentially zero compared to the interaction between car and air.

It's why the rolling road is in the wind tunnel and why the tunnel includes devices to remove the tunnel's own boundary layer just before the rolling road.
If you are more fortunate than others, build a larger table not a taller fence.

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Vanja #66
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Re: Mercedes W13

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ringo wrote:
15 Mar 2022, 14:37
No.The car is moving. relative motion. Road moving away from the car or car moving away from the road. whatever you want to choose.
And there is a boundary layer. always is.
From there is friction there is a boundary layer. It can never be zero.
Whatever you want to choose, there is no relative motion between air and road. If the car is moving, it's clear. If the car is standing, both the air and the road are moving at the same speed.

Just_a_fan wrote:
15 Mar 2022, 14:43
It's why the rolling road is in the wind tunnel and why the tunnel includes devices to remove the tunnel's own boundary layer just before the rolling road.
Nah, the rolling road and boundary layer suction devices are there because teams have way too much money and don't know what to do with it... :mrgreen:
And they call it a stall. A STALL!

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PlatinumZealot
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Joined: 12 Jun 2008, 03:45

Re: Mercedes W13

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tok-tokkie wrote:
15 Mar 2022, 09:55
I have only seen a few of the video clips linked on F1 Technical.
What has struck me is how close the Merc floor is to the road. It is just skimming the track in the vids I have seen.
The Red Bull, Ferrari (& McLaren?) are much further away.
There have been CFD shots showing the vortex running down the side of the floor forming a "skirt" to the floor &, hence, the tunnel.
In particular Red Bull has a wedge shaped vane creating a really strong vortex to provide this seal.
I suspect that Mercedes will adopt the same tactic to seal the floor. Then they need not run so close to the road. Then the choking problem will be resolved and the porpoising eliminated.
I actually wonder if they anticipated this all along (or certainly after Barcelona) and have the revised floor ready for the race.
Ooh The RedBull skims the road too! trust me.. you just need to see it in the corners! It also has a little bit of rake under it. Mercedes is indeed the lowest, and Ferrari has come out and said they are running the car high on purpose.

Amus and Scarbs are in agreement with me that Mercedes have the floor to remedy the porpoising back at the factory, and they are just pushing the set-up to the limits on the old floor to "learn to live with" the porpoising if it does come up again, because there might be tracks coming up where even a great floor can't fix it.
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nimoraca
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Joined: 16 Aug 2020, 11:43

Re: Mercedes W13

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If they do pull this off and are fastest again it will really be one of those "Fool me once shame on you, fool me for the 7th time, shame on me" situations.

Marty_Y
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Joined: 31 Mar 2021, 23:37

Re: Mercedes W13

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https://www.auto-motor-und-sport.de/for ... l-ferrari/

MERCEDES UPGRADE CAUSES NERVOUSNESS
An uncopyable idea
The lap times of the completely renewed Mercedes are not to be feared yet. But you could be. And just in case, the competition is preparing to do so. Their problem is that the W13's sidepod solution cannot be duplicated this season.
Michael Smith 03/15/2022

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SiLo
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Joined: 25 Jul 2010, 19:09

Re: Mercedes W13

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Vanja #66 wrote:
15 Mar 2022, 15:30
ringo wrote:
15 Mar 2022, 14:37
No.The car is moving. relative motion. Road moving away from the car or car moving away from the road. whatever you want to choose.
And there is a boundary layer. always is.
From there is friction there is a boundary layer. It can never be zero.
Whatever you want to choose, there is no relative motion between air and road. If the car is moving, it's clear. If the car is standing, both the air and the road are moving at the same speed.

Just_a_fan wrote:
15 Mar 2022, 14:43
It's why the rolling road is in the wind tunnel and why the tunnel includes devices to remove the tunnel's own boundary layer just before the rolling road.
Nah, the rolling road and boundary layer suction devices are there because teams have way too much money and don't know what to do with it... :mrgreen:
I would assume air follows similar principles as a fluid though right? Is that not why it's called Computational Fluid Dynamics? :P
Felipe Baby!

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ringo
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Joined: 29 Mar 2009, 10:57

Re: Mercedes W13

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Vanja #66 wrote:
15 Mar 2022, 15:30
ringo wrote:
15 Mar 2022, 14:37
No.The car is moving. relative motion. Road moving away from the car or car moving away from the road. whatever you want to choose.
And there is a boundary layer. always is.
From there is friction there is a boundary layer. It can never be zero.
Whatever you want to choose, there is no relative motion between air and road. If the car is moving, it's clear. If the car is standing, both the air and the road are moving at the same speed.

Just_a_fan wrote:
15 Mar 2022, 14:43
It's why the rolling road is in the wind tunnel and why the tunnel includes devices to remove the tunnel's own boundary layer just before the rolling road.
Nah, the rolling road and boundary layer suction devices are there because teams have way too much money and don't know what to do with it... :mrgreen:
The rolling road is to ensure the air and road have the same general velocity relative to the car.
The boundary layer suction device is just to adjust for the fact.
But boundary layer must exist.
The car collides with the air and squeezes it under the floor and basically pumps it. The floor then shears the air over the ground. The air will have relative motion between both it and the ground and the car. Think of plates inside a torque converter in an automatic transmission.

The windtunnel and rolling road tries its best to simulate this. It's this imperfection why the teams did not have porpoising cars in the windtunnel.

I do home CFD, I create the car model and create a ground. I set that ground surface to the same velocity of the air. That's pretty basic stuff, but it doesn't mean that's exactly what's happening in reality.

And you will see some relative motion there because the flow is not steady and there is compressibility. It's not steady state and perfectly laminar like what you study in basic examples. Real life it's even more different because the car is working the flow. In the wind tunnel the air is trying to work the car, so it's a loose approximation.
For Sure!!

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ringo
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Joined: 29 Mar 2009, 10:57

Re: Mercedes W13

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But to not go off topic.
I think Mercedes have a ride control/suspension problem more than sidepods.

I also feel Mercedes has a solution ready and were just exploring the limits as Scarbs suggested.

Looking at the car through the corners it looks very fast to me in some phases. I guess between mid and exit?
So they may be hiding pace.
For Sure!!

Henri
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Joined: 14 Jan 2022, 10:58

Re: Mercedes W13

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Once they fix the bouncing issue they can unlock the car

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Vanja #66
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Re: Mercedes W13

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SiLo wrote:
15 Mar 2022, 17:11
I would assume air follows similar principles as a fluid though right? Is that not why it's called Computational Fluid Dynamics? :P
Of course, gases and liquids are fluids...

ringo wrote:
15 Mar 2022, 17:35
No. The rolling road is to ensure the air and road have the same general velocity relative to the car.
The boundary layer suction device is just to adjust for the fact.
But boundary layer must exist.
The car collides with the air and squeezes it under the floor and basically pumps it. The floor then shears the air over the ground. The air will have relative motion between both it and the ground and the car. Think of plates inside a torque converter in an automatic transmission.

The windtunnel and rolling road tries its best to simulate this. It's this imperfection why the teams did not have porpoising cars in the windtunnel.

I do home CFD, I create the car model and create a ground. I set that ground surface to the same velocity of the air. That's pretty basic stuff, but it doesn't mean that's exactly what's happening in reality.

And you will see some relative motion there because the flow is not steady and there is compressibility. It's not steady state and perfectly laminar like what you study in basic examples. Real life it's even more different because the car is working the flow. In the wind tunnel the air is trying to work the car, so it's a loose approximation.
I honestly don't understand what you are trying to prove. Your assertion, formed by mixing up various effects and drawing some conclusions from that is entirely and completely wrong, from the very beginning. Any gust of wind will cause a boundary layer on the ground lasting as long as the gust lasts, about 1-2 seconds or so. Any steady wind will cause a boundary layer on the ground as well, but when the car goes through it this wind generates yaw and this is examined in CFD and wind tunnels. We aren't arguing this. However, do remember that the entire Earth's surface is covered in one big boundary layer, as a result of atmospheric movement. Yet, those are macroscopic phenomena and not taken into account when solving most of aerodynamic engineering problems.

Image

None of this is in any way related to venturi-tunnel floors choking and inducing porpoising. Just like none of those phenomena are meaningful enough to be simulated or examined by F1 or any other car aerodynamicists on a regular basis during car development. We know how many details F1 aero teams take into account and the fact they don't take wind-gust-caused and macroscopic boundary layer into account in CFD or wind tunnels speaks about its insignificance. They spend insane amount of time and money trying to align rolling road and free-stream velocity to who knows which decimal - precisely not to induce any boundary layer formation on the rolling road.

Now for the other part, which is also wrong. Yes, car colliding with the air is causing it to move relative to its previous position - pumps the air, as you've said it. However, due to the viscosity of the air, the fluid parcel on the ground will not move at all even when the car goes above it or when there is a wind gust. In fact, this car-induced air movement cancels any boundary layer formed by wind gusts of realistic air-speeds, relating to the point I made above about the insignificance of wind/thermal-induced boundary layers.

Viscosity is, of course, the very reason why boundary layers are formed in the first place - when the ground/wall is stationary and the air continuously moves over it. And this is why there are boundary layers on the whole car (of different lenghts, Re number, laminar, turbulent etc.), including the floor, but not on the road - the air does not move continuously over the road. Any longitudinal CFD cut-plot will show there is no boundary layer on the ground, like this screenshot of x-sweep CpT of FW43B from David Penner.

Image

To wrap this up, one more point. Planar fluid movement can't move a fluid parcel on any wall. This does not mean those parcels are fixed forever to the same point, as any perpendicular (upward) fluid movement can and does move them. This also happens when an F1 car goes over an observed fluid parcel and at some point there is a perpendicular velocity vector which does move the parcel away from the ground. This perpendicular movement does not induce another boundary layer - only movement parallel to the wall surface induces boundary layer.

Bear in mind there are young engineers and engineering students reading this forum next time you feel like using poorly understood arguments to persistantly back-up incorrect assertions. I was once one of those young students also, reading incorrect claims here sent me in the wrong direction a few times and I took me a while to understand that I don't actually understand something. As fellow engineers, we have a duty (at the very least to them) not to mislead them with false claims made by partial understanding of engineering problems, theory or empirical solutions.

That's it from my side, I'm out...
And they call it a stall. A STALL!

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Mchamilton
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Joined: 26 Feb 2011, 17:16

Re: McLaren MCL36

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MrGapes wrote:
15 Mar 2022, 13:30
With regards to the Mirrors, if any team was to go for something as extreme as Mercedes, or even similar I'm sure they need to alter there sidepods, the Merc style wing is essentially a element of the sidepod, and there are limits as to the amount of sections in the sidepod volume, thus teams with undercuts wouldn't be able to have the same solution, the closest team that probably could replicate it is McLaren, even then that would require major alteration to the current sidepods.
I dont think people are refering to the merc 'SIS wing' when they are talkin about the mirror stays. Theyre talking about the 6(?) flow conditioners mercedes have behind and to the side of the mirrors.
If they are talking about the SIS wing, then i dont know why because its clearly legal anyway.

rgava
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Joined: 03 Mar 2015, 17:15

Re: Mercedes W13

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The current discussion about the relative velocity between air and road in the venturi tunnels is going for sure going off topic in this Mercedes W13 thread.
I guess sooner or later a moderator can move it to its own thread.
Correct me if I'm wrong but the whole venturi system implies that the air is accelerating from the intake of the venturi to the throat. This acceleration I see it both in relation to the car and the ground in the opposite direction of the car's movement.
In this sense, I do see the formation of a boundary layer in relation to the ground as well as a thicker boundary layer in relation to the car's floor.
I'm aeronautical engineer, but a bit rusty in my understanding because I have not been working on fluid dynamics for a long time.
So excuse me if I'm saying something completely wrong. But I do appreciate if you can debate my understanding.

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