Will Gray

End of the wind tunnel?

Will Gray

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Manor F1 designer Nick Wirth has revealed the new team's car will be the first Grand Prix machine designed entirely using Computational Fluid Dynamics — but can it prove wind tunnels are a thing of the past?

Wirth confirmed last week that the new Manor F1 machine, which Wirth Research and sister company Digital Flow Solutions have been hired to develop, will be completed by the end of next month - and in doing so he confidently revealed the car will hit the track having never been near a wind tunnel.

The general long-held consensus of designers up and down the paddock, however, is that while CFD shows significant cost-effective potential and is moving forward at a rapid pace, there are still several years before a competitive car can be developed with confidence using solely CFD - and many believe taking that route could end in disaster.

Aerodynamics has long been one of the major performance differentiators in F1, but development has always required teams to create scale models to test aero modifications in wind tunnels week-in, week-out, costing millions of pounds in the process.

CFD instead uses computer programmes with mathematical equations to model how the air flows across the car. Although there is still significant costs in computing power and hardware, it's cheaper to run tests and can also better measure the effect of a car in a 'true corner' and include multiple parameters such as fluid flow, heat transfer and fluid-structure interactions which, because they run cold, wind tunnels cannot.

The CFD technique has always been limited by computing power, with even the best supercomputers unable to cope with the amount of mathematical processing required. But things are changing and new methods of hooking up servers along with new hardware technologies are rapidly increasing the capacity of these supercomputers to cope with the intense and fast-moving world of Formula One.

Now, calculations that literally used to take days can be completed in a matter of hours.

Renault recently invested in a major new CFD centre rather than building a second wind tunnel, and confidently predicted that the CFD testing will deliver 50 per cent of the performance gains developed by using a conventional wind tunnel at half the cost. But they still wouldn't trust it without testing those gains in the wind tunnel after going through the CFD work.

The nature of mathematical models is that they are never perfect — and so most teams believe that it is essential that results are cross-checked with a wind-tunnel model. That said, regulation-imposed restrictions on running time available in wind-tunnels and the cost required to develop the large models now used by most teams means going straight from CFD to full-size vehicle may be a viable alternative. But will the CFD results be good enough?

The aerospace industry relies a lot on CFD, but that has relatively simple geometry compared to racing cars. Wirth did develop the Acura LMP1 cars using only CFD, with great success, but again they are less complex than Formula One cars, particularly as they have covered wheels — and understanding flow interaction from open wheels is acknowledged as one of the most complex aspects of Formula One design.

There is no doubt that CFD has its strength in conceptual development, allowing designers to make quick major modifications - like altering wheelbase significantly - to get a baseline design understanding within a matter of hours, but many believe the complex detail on an F1 car is still out of reach for CFD modelling.

It's a brave move, then, for the newcomers to attempt to avoid a wind tunnel altogether — although it could also be a gamble born of necessity rather than choice.

The new teams were enticed into the sport by the promise of a budget cap that never saw the light of day and while efforts are being made to reduce costs, it would still take a great amount of money to compete with the current teams on the same playing field.

Slashing all wind tunnel costs will certainly help Manor's budget and if Wirth gets the CFD route right it could overcome the 'newcomer' disadvantage.

But if it goes the other way it could prove the CFD-only development concept is still a little ahead of its time.

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