joi, 15 noiembrie 2007

NASCAR drivers get HPC help with performance extremes

Measuring aerodynamic drag at 190 mph 'drives the engineers to a whole new level'

John Picklo, manager of high-performance computing (HPC) at Chrysler LLC, describes himself simply as an "IT guy" who's also a NASCAR fan. And he will be rooting Sunday for drivers of Dodge cars in the final race of this year's Nextel Cup.

The Chrysler engineers who work on the HPC systems that Picklo manages use the machines to improve race car performance. They work closely with the race car teams, and if one of their vehicles win -- as Dodge drivers Kurt Busch and Juan Montoya have in several Nextel races this year -- the driver and the racing team will be honored, the vehicle noted and congratulations shared around the company.

But no one will know, really, what role the HPC engineering staff had. Did the increase in fuel efficiency help? Or the design changes that improved air flow?

"We can make an improvement and get a couple of more miles per hour out of it, and really help -- and if the driver just skims the wall on lap 67, he can negate what we did," says Picklo.

"It is kind of like a football game -- everybody has to have to a good day. If one guy fumbles the ball, he can mess things up," says Picklo, who spoke at this week's SC07 supercomputing show in Reno, Nev. "We're doing our job, and so are the drivers, the teams and everybody else."

But Picklo, whose systems total 1,650 cores running in clusters in Linux and Unix environments, is certain of one benefit. Because these race cars operate at the extremes of vehicle performance, the HPC engineering work that has gone into them has had the "unanticipated benefit" of helping with vehicle performance for a wide range of vehicles.

"The extreme conditions of racing are teaching lessons that we might not have otherwise learned," says Picklo. Measuring aerodynamic drag for vehicles moving at 190 miles per hour "drives the engineers to a whole new level of skills," he says.

One example, he says, is the drag effect that large eddies of air have at such high speeds. By using computational fluid dynamics on the HPC systems, Chrysler engineers discovered how these eddies worked, their impact on vehicles and how to tune for it. That knowledge went back into their passenger car designs, Picklo says.

When vehicles travel at racing speeds, issues that might not be as pronounced at lower speeds may present themselves. For instance, the computer simulations show that a race car driving behind another vehicle may get restricted air flow, which can impact the engine. When that knowledge was applied to vehicle driving behind a large truck on a highway, engineers saw the same reduced air flow, says Picklo.

This ability "to develop more detailed fluid dynamic models for extreme conditions" has taught engineers a lot, says Picklo: "If you never think about what happens at 190 miles an hour, you might not realize that the same effects translate back into passenger vehicles."

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