Michael Waltrip Racing is fresh off a spate of recent wins and its best season since its 2007 inception as a NASCAR racing team. Along with rising stars Clint Bowyer and Martin Truex Jr., who helped earn the team its first two Chase for the Sprint Cup berths, Michael Waltrip Racing is crediting changes to its aerodynamics design process as a key to its new competitive edge.
Likening the cutthroat competition of NASCAR to a "arms race," MWR aerodynamics manager Andy Hogg told us testing through digital simulation better prepares his team for battle. "Speed is crucial and not just on the track," he said in an interview. "Design speed is a critical measure of our success."
Michael Waltrip Racing's secret weapon coming off of its competitive NASCAR racing season is the combination of CD-adapco's Star-CCM+ CFD tools and wind tunnel testing. (Source: Michael Waltrip Racing)
MWR's traditional aerodynamics design processes were not that nimble, according to Hogg. The organization is tasked with making 35 cars a year to compete and it's always relied heavily on wind tunnel testing to explore different design ideas for modifying the standard NASCAR design to get a leg up on the competition.
The problem with that approach was that the team was limited in terms of how many ideas it could try out in the wind tunnel, and it was really a matter of guesswork as to which ones had the best potential, Hogg said. "Without CFD, we didn't really understand the flow characteristics of the car so it was hard to make changes that worked," he said. "It was more of a guess and check."
Today, while it doesn't use the wind tunnel any less (MWR tests about 30 design changes per month in a wind tunnel), it does employ the technology differently -- specifically, in a more intelligent fashion. Leveraging cd-Adapco's Star-CCM+ Computational Fluid Dynamics (CFD) software, MWR engineers now run all possible ideas through digital simulation to prove out their viability before hitting the wind tunnel with a select few for validation. Hogg said:
Before, we had more ideas than we could test, but we would just guess at the ones with the most potential. Today, we might run through 60 ideas a month in simulation and pick the best 30 from CFD. It gives us a much better shot of them working out in the wind tunnel.
While the NASCAR teams work off a standard design, Hogg said there's a huge amount of tweaking and refining of parts and small improvements every week to get that tiny leg up on the competition. "People don't realize how much innovation and rate of improvement determines a team's success during the season," he said.
Having the flexibility to fully explore a range of possible design options in the digital world is critical for a team that is a relative newcomer in the competitive and well-established world of NASCAR. Moving forward, Hogg expects to take advantage of cd-Adapco's cloud-based simulation capabilities, especially when the new car body design for next year is announced in the next couple of weeks. Cd-Adapco's Power-on-Demand offering lets customers run Star-CCM+ in a cloud-based session using on-demand cloud computing services like Amazon EC2. Running CFD simulation in the cloud will allow a bunch of design work to be done in parallel, Hogg said, which is critical to achieving that edge right out of the gate:
We already have time on [cd-Adapco's] cloud offering on hold, and as soon as we get the go-ahead that this is the package, we're going to swamp the cloud with simulations -- way more than we could ever do on our own hardware. That gives a short-term burst (for simulation), which we couldn't afford to maintain all year round.
NASCAR is one of the most interesting "playgrounds" for engineering and cutting edge tools. Before I became a NASCAR fan, I thought they just got a showroom car and put a huge motor in it. Oh no, so much more! Design of roll cages and frames for driver safety, spring rates and shock response under varying conditions, engine building and tuning, aerodynamics. etc. F1 racing seems to have more electronic control over various parameters while the car is on the racetrack, while also using engineering applications in the design and test phases. A lot of engineers have found their "happy place" in the world of motorsports.
Thanks for the added detail, Bob. You're absolutely right about the challenge of modeling to reality, however. While your 25% percent approximation figure has been greatly improved with the latest technology, it's still one of the challenges around CFD and simulation in general.
Beth, right after the SIM Center moved from Mississippi State to UT Chattanooga, the Center arranged an open house for engineers interested in learning more about CFD. I went. The prospect of combining fluid dynamics with CAE really fascinated me. I was blown away by the capability of the software and the modeling techniques. The first demonstration used a tractor/trailer combination and modeling air flow around the cab and trailer at various speeds. The second model demonstrated air flow around an F- 18 Hornet and how that air flow varied when airfoil surfaces came into play. The graphics were absolutely stunning. One thing I came away with was the close correlration between model and reality. In the "old days", reality was hard to come by due to issues with the mathematical algorithm. An approximation within 25% was considered to be "state-of-the-art". Times have really changed.
Thanks Bob. That sounds like quite an informative presentation. May I ask what the purpose of the demonstration was and who the audience was? Was it's purpose to promote CFD specifically?
Beth, one of the most fascinating demonstrations I have seen in the recent past was given by the SIM Center at the University of Tennessee at Chattanooga. It was a demonstration of the power of CFD in investigating air movement around 18 wheelers traveling at varying speeds. Grant money was furnished by the National Highway Traffic Safety Administration (NHTSA) and Peterbuilt. As a part of the demo, we were able to see how variations in cowling and "hardware" made differences in air patterns slipping over exterior surfaces of the cabs and trailers. I'm sure NASCAR could benefit from CFD and save hundreds of hours devoted to "cut and try". Great article.
Michael Waltrip was going for the win on the last lap of the race at Talladega Superspeedway (Sunday, Oct 7, 2012)...so he did a good job in putting himself in a good position at the end of the race. Unfortunately, he got caught-up in a huge last lap crash, finished 25th.
I did enjoy the 54 lead changes during the 500 mile race (and that's only "official" lead changes at the start/finish line), as well as the fast 171 mph average speed. The high-speed race was all about the use of aerodynamics, including drafting.
@RICKZ28: The arms race analogy is certainly different, but the Michael Waltrip team's choice of words, not mine. And you are right, aerodynamics is a huge design challenge for these racing teams. In fact, there are many, many stories about other race car teams leveraging advanced simulation software to do more of the same. Interesting, because these teams are out in front in terms of how they're incorporating simulation into their design workflows compared with many engineering organizations in traditional companies.
Interesting analogy...NASCAR is like an "arms race". Of course the arms race is within the rules, and it depends on how the drivers and teams perform during the race. The competition is cutthroat, and that's part of the reason for NASCAR's popularity.
As for aerodynamics, it definitely plays a big role on the longer faster tracks. A damaged car body at Daytona or Talladega can rarely keep pace with the front runners, aerodynamics is just too critical at 190-210 miles per hour. Many non-fans have noticed the NASCAR "drafting", where at high-speed, two or more cars lined-up are faster than one car alone.
Watch the NASCAR race at Talladega Superspeedway (2.66 mile tri-oval with 33 degree high-bank turns) this Sunday (Oct 7th) to see why aerodynamics is so important in high-speed races. There is usually a huge number of lead changes during the race, 50 or more lead changes is not uncommon. The race record is a 188 mph speed average, qualifying record 212 mph. Frequently there is last lap passes to win the race, as the driver's know how to use aerodynamics to make passes ("overtaking" for you F1 people).
@TJ: Wind tunnel testing is definitely still necessary, no doubt. What the team at Michael Waltrip is saying it that by leveraging simulation (and eventually even more high performance compute horsepower offered by the cloud), they can test out more possibilities and then use the wind tunnel testing (which is limited due to budgets) for validation of the best designs. Helps them explore more possibilities more efficiently and cost effectively--a refrain I hear consistently from simulation users.
This is a great use of simulation, Beth. Incredibly improved efficiency. This same approach is getting used in building plants and setting up systems. simulation prior to build is saving both time and money.
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