F1 Evaluating ‘Wheel Arches’

[Just_a_fan]

With regards to the diffuser, I'd be highly surprised if they weren't picking up water from the surface and spitting it out.

I'd be amazed if the cars were lifting water off the track with the under floor aero at all - there will be some localised condensing out of moisture from the air (we see that under the front wing on various shots, for example) but the water on the track is staying there until the tyres get involved. The tyres are lifting the water (it's their job to do that, after all) and the aero is then throwing that up in the air - the aero was designed specifically to lift the car's wake high above the track so that it doesn't affect the following car. It's doing that and pulling the spray from the tyres up with it.

[mwillems]

With regards to the diffuser, I'd be highly surprised if they weren't picking up water from the surface and spitting it out.

I'd be amazed if the cars were lifting water off the track with the under floor aero at all - there will be some localised condensing out of moisture from the air (we see that under the front wing on various shots, for example) but the water on the track is staying there until the tyres get involved. The tyres are lifting the water (it's their job to do that, after all) and the aero is then throwing that up in the air - the aero was designed specifically to lift the car's wake high above the track so that it doesn't affect the following car. It's doing that and pulling the spray from the tyres up with it.

But the spray comes down again in a mist and is still a problem, and not all would be lifted over, you'd think?

We will find out later this year but even the FIA are saying they need to analyse how much is being pushed out by the diffuser.

How do you think the extreme pressures of the floor doesn't apply to the water in that low pressure zone? I just imagined so.e of it would expand to finer particles and become part of the flow.

[Just_a_fan]

With regards to the diffuser, I'd be highly surprised if they weren't picking up water from the surface and spitting it out.

I'd be amazed if the cars were lifting water off the track with the under floor aero at all - there will be some localised condensing out of moisture from the air (we see that under the front wing on various shots, for example) but the water on the track is staying there until the tyres get involved. The tyres are lifting the water (it's their job to do that, after all) and the aero is then throwing that up in the air - the aero was designed specifically to lift the car's wake high above the track so that it doesn't affect the following car. It's doing that and pulling the spray from the tyres up with it.

But the spray comes down again in a mist and is still a problem, and not all would be lifted over, you'd think?

We will find out later this year but even the FIA are saying they need to analyse how much is being pushed out by the diffuser.

How do you think the extreme pressures of the floor doesn't apply to the water in that low pressure zone? I just imagined so.e of it would expand to finer particles and become part of the flow.

Yes, the "fog" is created by the water being lifted and then hanging in the air.

And the floor doesn't experience "extreme pressures". Certainly not large enough pressure drops to cause water to be sucked from the surface of the tarmac. Yes, pressure drops will allow water to condense out of the moist air, but we're not vacuuming the water off the ground. Most of the water involved is from the tyres doing their job as we know, the tyres disperse 85L / s at 300km/h (yes, no one is likely going that fast in heavy rain but it's the figure oft quoted). That's each tyre. So the cars could be throwing over 300L/s in to the air.

At 300kph, a single intermediate tyre can disperse around 35 to 40 litres of water per second. That means that a Formula 1 car at full speed on the straight can shift around 150 litres of water per second running on the intermediate. If it's on the full wet, that figure can be doubled. An astonishing amount of water.

https://www.pirelli.com/global/en-ww/ra ... a-1-52943/

Obviously they don't generally run in water that deep and certainly not at 300km/h. But the fact remains that each car is throwing 10s of litres of water upwards per second from the tyres.

Here's a nice example of what's happening - Max driving through some standing water - one can see the huge amount of spray the rear tyre is generating as water is thrown sideways and upwards by it. The front tyre has done likewise and the spray from that is over the rear tyre and being dragged in to the cloud too. The water from the rear is then picked up by the wake to add to that cloud. And that big cloud is from a bit of standing water not much wider than the length of the car. Make it the full track and add 19 other cars and you have the problem facing F1.



Frankly, I can see F1 moving towards not running if there is more than a very light amount of rain. Any solution is unlikely to be that effective unless it encloses the tyre and directs the water back on to the tarmac and/or laterally in a stream (not small droplets).

[mwillems]

I'd be amazed if the cars were lifting water off the track with the under floor aero at all - there will be some localised condensing out of moisture from the air (we see that under the front wing on various shots, for example) but the water on the track is staying there until the tyres get involved. The tyres are lifting the water (it's their job to do that, after all) and the aero is then throwing that up in the air - the aero was designed specifically to lift the car's wake high above the track so that it doesn't affect the following car. It's doing that and pulling the spray from the tyres up with it.

But the spray comes down again in a mist and is still a problem, and not all would be lifted over, you'd think?

We will find out later this year but even the FIA are saying they need to analyse how much is being pushed out by the diffuser.

How do you think the extreme pressures of the floor doesn't apply to the water in that low pressure zone? I just imagined so.e of it would expand to finer particles and become part of the flow.

Yes, the "fog" is created by the water being lifted and then hanging in the air.

And the floor doesn't experience "extreme pressures". Certainly not large enough pressure drops to cause water to be sucked from the surface of the tarmac. Yes, pressure drops will allow water to condense out of the moist air, but we're not vacuuming the water off the ground. Most of the water involved is from the tyres doing their job as we know, the tyres disperse 85L / s at 300km/h (yes, no one is likely going that fast in heavy rain but it's the figure oft quoted). That's each tyre. So the cars could be throwing over 300L/s in to the air.

At 300kph, a single intermediate tyre can disperse around 35 to 40 litres of water per second. That means that a Formula 1 car at full speed on the straight can shift around 150 litres of water per second running on the intermediate. If it's on the full wet, that figure can be doubled. An astonishing amount of water.

https://www.pirelli.com/global/en-ww/ra ... a-1-52943/

Obviously they don't generally run in water that deep and certainly not at 300km/h. But the fact remains that each car is throwing 10s of litres of water upwards per second from the tyres.

Here's a nice example of what's happening - Max driving through some standing water - one can see the huge amount of spray the rear tyre is generating as water is thrown sideways and upwards by it. The front tyre has done likewise and the spray from that is over the rear tyre and being dragged in to the cloud too. The water from the rear is then picked up by the wake to add to that cloud. And that big cloud is from a bit of standing water not much wider than the length of the car. Make it the full track and add 19 other cars and you have the problem facing F1.

https://racer.com/wp-content/uploads/si ... 2131-2.jpg

Frankly, I can see F1 moving towards not running if there is more than a very light amount of rain. Any solution is unlikely to be that effective unless it encloses the tyre and directs the water back on to the tarmac and/or laterally in a stream (not small droplets).

I'm not suggesting the pressure will suck the air from the tarmac, just that the pressure and flow and the behaviour of the vortices that seal the floor is enough to disturb plenty of water for the diffuser to spit out. And if the wheel arches on the front wheels suppress water from flying into the air, isn't there yet more lo level water droplets being potentially fed into the floor?

You may be right about not running, the FIA themselves seem unsure of their own attempts to create a solution and seem to be throwing at the wall and seeing what sticks.

[SiLo]

I'm fairly certain a diffuser on an F1 car can lift water from the tarmac. It's literally visible in the picture of the Red Bull above, if it was only from Tyres, there wouldn't be so much spray centrally behind the rear wing. Diffusers contribute huge amounts of downforce overall for the car, which will max out in the tonnes, easily enough to lift water from the surface of the track.

There is a reason spray has gotten worse and worse over the years, the cars have become more and more efficient in diffuser design.

[Just_a_fan]

I'm fairly certain a diffuser on an F1 car can lift water from the tarmac. It's literally visible in the picture of the Red Bull above, if it was only from Tyres, there wouldn't be so much spray centrally behind the rear wing. Diffusers contribute huge amounts of downforce overall for the car, which will max out in the tonnes, easily enough to lift water from the surface of the track.

There is a reason spray has gotten worse and worse over the years, the cars have become more and more efficient in diffuser design.

The tyres lift the water, the aero drags it in and up - the aero is designed to drag air in and lift the wake - that's exactly what was intended. And you can see it all happening in this shot of intermediate and wet weather tyres:


The inters lift less water so there is less spray. The wets lift more water - more spray. One can see the water lifted by the tyres being dragged in to the wake behind the cars. The air behind the car is moving with the car to a degree - that's what causes the tow and what messes with the following car after all - and so the lifted water is circulated up by the general circulation that exists immediately behind the car.

As for tonnes of downforce from the diffuser, really?

[mzso]

Yes I agreed, that was quite different, there was a real danger in 2005, here there would not be. But the statement was that no teams have done it and it wasn't totally correct.

Yeah, but you moved from track conditions to unraceable hardware, so not talkig about the same thing. No matter it's beside off topic anyway.

With regards to the diffuser, I'd be highly surprised if they weren't picking up water from the surface and spitting it out. It is certainly part of the programme to asses how much it is spraying, in fact the whole testing is around what is possible as it is very hard to model water droplets in CFD. Hence they are trying the physical tests in lieu of any design that can be tested properly in CFD. The tests at Silverstone were innefective so now they have another go and they will measure the diffuser spray then. it is quite possible that the diffuser spray renders any work on the wheels pointless. Time will tell.

I think it's only reasonable to expect the diffuser to pick up water if there's a thick water layer. Water stick to surfaces rather well. Even then I only can imagine the suction picking up big drops, if anything.
I think as much as the issue is concerned it's 100% caused by the tires. They aerosolise the water menchanically, which is then caught by the airflow (of the diffuser as well).

[mzso]

The tyres are lifting the water (it's their job to do that, after all) and the aero is then throwing that up in the air - the aero was designed specifically to lift the car's wake high above the track so that it doesn't affect the following car. It's doing that and pulling the spray from the tyres up with it.

To be fair I don't see being worse than it used to be in the past (like Häkkinenen-Schumacher times) at all. It's just easy to point at the new underside. The main difference is that they're making a clown show of this as well.

And anyways if the car needs to go down (downforce), air needs to go up.

[mzso]

I'm fairly certain a diffuser on an F1 car can lift water from the tarmac. It's literally visible in the picture of the Red Bull above, if it was only from Tyres, there wouldn't be so much spray centrally behind the rear wing. Diffusers contribute huge amounts of downforce overall for the car, which will max out in the tonnes, easily enough to lift water from the surface of the track.

There is a reason spray has gotten worse and worse over the years, the cars have become more and more efficient in diffuser design.

You're projecting things into it. And downforce comes from the difference in high pressure atop, compared to the low pressure on the underside. It's not grabbing to the track surface as such. Besides, the area where the floor works is in the square meter range, not concentrated like a vacuum cleaner.

And it hasn't got worse. Only the whining did.

[Just_a_fan]

The tyres are lifting the water (it's their job to do that, after all) and the aero is then throwing that up in the air - the aero was designed specifically to lift the car's wake high above the track so that it doesn't affect the following car. It's doing that and pulling the spray from the tyres up with it.

To be fair I don't see being worse than it used to be in the past (like Häkkinenen-Schumacher times) at all. It's just easy to point at the new underside. The main difference is that they're making a clown show of this as well.

I think it's an issue caused by changed levels of risk acceptance. People dying in conditions of poor visibility will tend to focus the minds of those making decisions at other events. The FIA and the drivers are concerned about the safety aspect - and rightly so.

However, one either
a: accepts the situation/risk and carry on,
b: make changes to the car/track to reduce the problem, or
c: decide the risk is too great and avoid the problem by not racing in poor conditions.

Some people will say "a" is ok, most are likely to say "b" is the preferred outcome, and I would guess not many would consider "c" to be a good option.

The issue is how to do "b".

And anyways if the car needs to go down (downforce), air needs to go up.

How very Newtonian of you.

[SiLo]

I'm fairly certain a diffuser on an F1 car can lift water from the tarmac. It's literally visible in the picture of the Red Bull above, if it was only from Tyres, there wouldn't be so much spray centrally behind the rear wing. Diffusers contribute huge amounts of downforce overall for the car, which will max out in the tonnes, easily enough to lift water from the surface of the track.

There is a reason spray has gotten worse and worse over the years, the cars have become more and more efficient in diffuser design.

The tyres lift the water, the aero drags it in and up - the aero is designed to drag air in and lift the wake - that's exactly what was intended. And you can see it all happening in this shot of intermediate and wet weather tyres:
https://pbs.twimg.com/media/F3hCt_DXgAA ... name=large

The inters lift less water so there is less spray. The wets lift more water - more spray. One can see the water lifted by the tyres being dragged in to the wake behind the cars. The air behind the car is moving with the car to a degree - that's what causes the tow and what messes with the following car after all - and so the lifted water is circulated up by the general circulation that exists immediately behind the car.

As for tonnes of downforce from the diffuser, really?

Sorry I worded my bit about diffuser downforce incorrectly, when I said max out I meant the whole car, and that the diffuser accounts for a majority of that (around 60% is my understanding).

[FW17]

I doubt the diffuser or the floor of the car can lift the standing water and cause atomization like what the tyres do.

Diffusers only seems to throw the water up much higher what comes off the tyres.

If the wash from the tyres are prevented from atomization and made to form larger droplets by a set of louvers of a detector, some of the wet race visibility issues may be sorted.

[SiLo]

So everyone is in agreement that the water flowing up centrally, very high behind the rear wing, is flow effectively from the tyres?

Does this not seem like a lot of flow affected by the tyre, which teams desperately try to avoid with complex flow structures underneath the car, and as much outwash as possible?

[zioture]

F1 SPRAY GUARD how could it be real

[organic]

We will evaluate the 'mudguards', systems, which can limit the spray phenomenon,” he added. “But we are also evaluating the possibility of intervening on the diffuser outlet.

“It is an important issue

There's no particular solution at the moment. But, as you saw in F1, there was the first learning step towards some solutions.

“I know there was a bit of criticism, and I read it was a failure, but in any of these situations, you've got to try things. And that's exactly what we did.

“It certainly wasn't a failure, because we learned a lot from it. And the next iterations will get better and better.”

https://www.autosport.com/f1/news/f1-ey ... /10514198/