CFD discussed by Honda’s Henrik Diamant
CFD is often described as ‘a wind tunnel in a computer’. It exists because the laws of physics that
dictate how a fluid or a gas flows across an object can be accurately modeled using complex mathematics. In other words, a computer can analyze the aerodynamic properties of a part before it’s been manufactured. The cost and time benefits of this are self-evident.
“Although the governing Navier-Stokes equations date back almost 200 years and the basic principles of CFD were invented in the 1930’s, it wasn’t until the mid-’90’s that the idea took root in Formula One" says Henrik Diamant, the Head of CFD for the Honda Racing F1 Team. “It was only after the development of powerful computers that we were able to apply this technology effectively to Formula One."
Honda’s supercomputer is certainly something to behold. Boasting its own, dedicated room, the water-cooled computer employs hundreds of processors, linked in parallel. The exact specification is a closely guarded secret but suffice to say that it’s perhaps a thousand times more powerful than a domestic PC. “Calculations that, literally, used to take days can now be completed in a matter of hours," explains Diamant.
Diamant began his career as a CFD software consultant at Fluent in Sheffield. “It was a natural stop-gap for me after leaving university, but I always wanted to work in Formula One." Although the technology is used throughout industry, F1 is pushing the boundaries. “CFD is widely used in the aerospace industry, but geometries are comparatively simple. In its detailed geometry, Formula One is regarded as the cutting edge with its wings, complex bodywork, cooling arrangements, engine bay and last but not least very complex geometry inside the wheels."
The pace of development in F1 is also unlike any other industry. “The lead times for aircraft design might be 5-10 years," says Diamant. “But in Formula One, we’re introducing update kits on a monthly basis."
Diamant and his team of fifteen people play both the long and short game. “The latest computing power does open up more possibilities for blue sky thinking. If you wanted to try stretching the car by 200mm, a model could be generated and results could be analyzed within 24 hrs. The technology has been very useful for analyzing the impact of the new regulations that will be introduced in 2009."
Detailed work is also undertaken to optimize new parts before they’re tested on the car. This has become particularly important after testing restrictions were imposed on the teams at the start of the 2007 season. With every lap now crucial, any testing work that can be done away from the circuit is hugely valuable.
Working in a computer simulated environment has a number of advantages compared with more traditional techniques, including wind tunnel testing. A wind tunnel cannot simulate the effect of a car in a ‘true corner’, for example, and nor can it analyze the impact of two cars following each other.
“Although the majority of our work is done steady state, we can look at the telemetry to see how the car sits on the track at each instance and use this as the basis of our simulation," says Diamant. “In the future we hope to be able to analyze the car around the whole of the race track and to optimize it accordingly. We will also be able to look in more detail about how the cars interact with one another."
CFD technology has progressed beyond recognition in recent years, but the day when an entire car is designed and tested on computer is still some way away. “A wind tunnel is still a critical part of the process," continues Diamant. “We need to correlate our results with wind tunnel tests. We need to measure the forces and the pressures acting on the physical objects, to ensure that our CFD results do not deviate from ‘reality’."
There can also be no substitute for physical tests on the race track. No matter how sophisticated the
computer is, there are some variables that it cannot compute and the CFD chief is quick to acknowledge the value of the ‘real world’. “There is always a value to me attending the tests. When you see the car performing at close quarters, it allows you to understand the physical pressures and imagine the forces. It helps you to understand the violence of the movements, especially when a car runs across the curbs. It’s very different from watching a car on a computer screen and it’s fun – we’re all racers." The successful Formula One team of the future will continue to blend together the benefits of CFD, wind tunnels and on-track performance testing.
Diamant has been working in Formula One for almost a decade but is constantly surprised by the pace of change. “When you look at the cars of ten years ago, it was staggering how simple they were. Investment in tools and computers has created cars with an extraordinary attention to detail."
As cars become ever more sophisticated and computing power increases yet further, it’s clear that Diamant’s merry band of unsung heroes will play an increasingly important role. It might not be sexy, but never underestimate the value of Computational Fluid Dynamics.
Honda Racing F1 Team