2021 Williams F1 Computational Fluid Dynamics

That's an awesome video clip, thanks for sharing :)

Very cool, but yeah anyone with the competency and computing power to do actually decent F1 CFD wouldn't be posting it on the internet.

The teams themselves have a hard enough time getting a model to match their actual car.

Can’t upvote this enough. I actually include an hour of rant in my Fluids class where we dissect CFD results from blogs or LinkedIn - hypersonic reindeer for Christmas are fun and obviously a joke, but everything presented sincerely, like all the Cybertruck analyses when it was revealed, are mostly irrelevant. Don’t trust CFD results if you don’t know every aspect of them.

It’s “dangerous” now in the sense that people just have to click a button and are led to believe that meaningful results are being produced without a thorough study.

Strategy:

Leak CAD model, get other people to do simulations for free!

Is that limitation to reduce the cost of competing for those who don't have big GPU farms?

Actually, the limit is in TFLOPs, and the use of CFD is audited.

What? How is that even enforced?

Ironically, the allowance for CFD time is scaled based on the reversed world championship points order, and Williams was dead last, so they should have the most CFD time of any of the F1 teams.

In 2017, Ars Technica did a deep dive into computation in Formula 1 (https://arstechnica.com/cars/2017/04/formula-1-technology/).

Some relevant quotes:

> For example, each Formula 1 team is only allowed to use 25 teraflops (trillions of floating point operations per second) of double precision (64-bit) computing power for simulating car aerodynamics.

> Oddly, the F1 regulations also stipulate that only CPUs can be used, not GPUs, and that teams must explicitly prove whether they're using AVX instructions or not. Without AVX, the FIA rates a single Sandy Bridge or Ivy Bridge CPU core at 4 flops; with AVX, each core is rated at 8 flops. Every team has to submit the exact specifications of their compute cluster to the FIA at the start of the season, and then a logfile after every eight weeks of ongoing testing.

> Everest says that every team has its own on-premises hardware setup and that no one has yet moved to the cloud. There's no technical reason why the cloud can't be used for car aerodynamics simulations—and F1 teams are investigating such a possibility—but the aforementioned stringent CPU stipulations currently make it impossible. The result is that most F1 teams use a somewhat hybridised setup, with a local Linux cluster outputting aerodynamics data that informs the manufacturing of physical components, the details of which are kept in the cloud.

> Wind tunnel usage is similarly restricted: F1 teams are only allowed 25 hours of "wind on" time per week to test new chassis designs. 10 years ago, in 2007, it was very different, says Everest: "There was no restriction on teraflops, no restriction on wind tunnel hours," continues Everest. "We had three shifts running the wind tunnel 24/7. It got to the point where a lot of teams were talking about building a second wind tunnel; Williams built a second tunnel.

With the new cost cap in F1 (https://www.autoweek.com/racing/formula-1/a35293542/f1-budge...) (which notably excludes driver salaries), it would be interesting to know how much these on-prem clusters cost to operate.

The limit is in FLOPS but CFD is memory bound. To get round the limit, AMD made custom CPUs with restricted floating point performance to allow quadrupling the number of cores.

https://www.reddit.com/r/formula1/comments/g4sboe/custom_cpu...

A million times this. Honda published a teeny bit of data in the mid 2000s but that's basically it

Regulations always change and what was legal today might be banned tomorrow and be legal again (like Williams active suspensions from the Mansell era)

It doesn't make sense to make all data public when there might be something the FIA or other teams didn't know about and might be useful in the future.

F1 is all about living on the edge of what's allowed by the rules, and more often than not crossing that line and hoping not to get caught by the FIA. There's a fantastic interview with Ecclestone, Withing and Piquet (1) where they reminisce the olden days and have a laugh admitting their Brabham car was so illegal they would have been disqualified by the FIA had they knew that. 2019 Ferrari had an amazing engine and then they got caught doing tricks with the fuel sensors.

1: https://www.youtube.com/watch?v=fMsaUgXf3v4

I remember reading a friend's "owner's manual" for a honda road-racing (only) motorcycle years ago and it was amazing.

A normal motorcycle owner's manual is almost 100% propaganda by weight.

it's basically legalese regarding injury, legalese regarding warranty type stuff, a few specificaitons, a bit of sort of fantasy maintenance which mostly segways into... "contact a dealer", then lists dealers

In comparison the road-racing honda manual talked about reality. written by engineers, not lawyers.

For example, I recall it told you how to gear the bike for different speeds (the kinds that would lose your license, wallet and prospects on the street)

It also had carb (yes) settings for different track temperatures and all the maintenance intervals were in hours of use.

I think this kind of stuff is a goldmine, and can really educate.

iRacing? Nah, they will add it to rFactor2 and Assetto Corsa.

Do you know any more details about the leak? The article didn't really discuss it.

The regs are changing anyway so the risk is basically zero even if they had something worth stealing.

Since Williams defines the very bottom of the race grid, they don't have much to hide in terms of technology. So releasing a 3D model of their car in this form is nothing that would harm the team at this time.

That certainly was the case in the past with the whole 'blown diffuser' situation which led to cars' engine maps being specifically created to allow lots of volume of air through the exhausts even when they weren't generating much power to take advantage of this - listen to the exhaust sound in mid corner of this era F1 car and you'll hear what I mean (I think it was around 2011 and Red Bull were the best at it, but I think many did it to a degree).

Similarly, a lot of the tricky aerodynamic effects in F1 come off the tyres (tyre squirt etc.) so without modelling those you're not getting a great view of the bigger picture.

In a similar vein I remember reading that one of the reasons for the CFD restrictions was because the bigger teams were starting to spend a lot of money modelling the aerodynamics of the tyres as they oscillated in corners (because F1 tyres have a relatively high sidewall they deform a lot through corners, then if a wheel lifts a little e.g. bouncing over a curb, then the whole tyre starts oscillating laterally.) Sounds very interesting but a bit of a CFD nightmare!

Agreed, that definitely sounds fishy as hell.

Organizations where the big $ is on intel property and R&D wouldn’t be dumb enough to give the actual schematics to some random intern building an app. There are some serious security controls and mNDA around that data, for all internal parties, external parties and suppliers. Think about it, they must collaborate with dozens if not hundreds of parties to get to a finished products, and some amount of information must be circulating to achieve the purpose of their relationships. If those were to leak - they’d leak to the competitors first and it’d be a disaster for the entirety of the upcoming year(s) as the improvements tied to their new designs would now be considered available on all cars. It doesn’t take two dummies to think about that, soooo.. to avoid losing hundreds of millions, what do you do as an organization? Data classification, risk assessments, tight security controls, procedures, and finally mNDAs for the instances when data do have to be shared.

Furthermore, as it was pointed out on Reddit, the model appears to be made of parts that are valid for 2020 regulations, some parts for 2021.. in other words, it’s just scrap.

You can get quite detailed timing data from the F1 app. If you have the speed and time data for a sector that's completely full throttle and straight you can calculate quite a lot.

This year's rule change is about reducing downforce and so slowing cars down to protect the tires. Next year is about following.

The pushed the new cars to next year, this year they wanted to cut downforce levels as the load was too much for the tyres last year.

To each their own perhaps, but I find F1 very exciting. Even despite Mercedes's recent dominance, there is plenty of great midfield action, strategic decisions, uncertainty due to safety cars or weather, and teammate battles that make each race a fun watch.

It's worth noting the current rule set is trying to optimize for spectator moments, safety and budget constraints. An F1 series unruled at this point would be a case of biggest pockets wins, and the racing wouldn't be close at all. I like to think of F1 as just a big go-cart race. The cars are obviously on the edges of performance inside the rules, but the cars are still homologated.

The really interesting racing has been in Time Attack and grassroots leagues in my opinion. I forsee an end to F1 soon enough, the budgets are big and it's no longer a good platform for R&D given manufacturers will start to ditch consumer ICE anyway. Whereas Time Attack and other leagues are more about developing enthusiast level performance fabrication shops and parts which is something that will go on in to the future.

Depends what you want from a series I guess.

I see F1 as high budget soap-opera/reality-TV with a racing series setting. I can't relate to the people in the same way as you might with the "dirty dozen" approach but the drama is there nonetheless.

I used to love F1 as an engineering research unit for the world. But once regulations started banning technologies - and even relatively simple tweaks! - left right and centre it lost that shine.

I wish F1 would largely throw away the regulations again.

Keep general safety regulations, a safety cell and 4 wheels, set the physical parameters for the car like size and weight with an 80kg driver, maybe specify some aerodynamic condition for trailing air and limit the unobtanium material use.

I think limiting $ spent should be done by full specifications of cars to be released after 3-5 years. It is only worth spending money to get an advantage. If all your competitors are going to have your research in a few years then why spend so much? Also, ALL the engineering fanciness is released for the world to benefit.

Then, when cars get too fast. Reduce the size/weight of the car, while keeping safety cell and wheels the same.

"Oh, your 2m wide car goes too fast? Try it next year at 0.8 the size."

Eventually it will be go-karts again. But of the most brilliant engineering.

If you subscribe to F1TV you get timing data in form of additional screen which you can view. Apart of that, there were several attempts in the past to extract timing data from from live streams, which stopped around 2016 when the API was changes. So to my knowledge, there is no free API for that. If there was payed version, I would be also interested, but I don't know about it either. The thing is that F1 considers this traditionally very sensitive information and is unlikely to make it public any time soon.

You can extract the data by sniffing the app's traffic, but it's not easily done.

Live timing isn't that hard, live pseudo-telemetry like the app delivers is really hard.

Also you ain't getting it for free unless you're super lucky - not that kind of industry. Ergast has non-live data, however.

I read an article[1] a while ago where some people made a dashboard with all streams and data. Never tried it though. The application is called race control and is opensource [2]. If the app is not what you mean, their reverse engineered api client might help?

1. https://tweakers.net/reviews/8900/naar-diverse-f1-streams-te... (dutch)

2. https://github.com/robvdpol/RaceControl

Under what authority / jurisdiction would the author get in trouble for doing these computations? Surely the FIA doesn't have any authority over random civilians.