AN-Solutions Spring '05Final

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AN-Solutions Spring '05Final











CFD Update:
Whats New in Computational Fluid Dynamics
During the past 14 years, solar car racing has becomeincreasingly popular, and vehicles have become considerably more sophisticated as they evolved fromtypically heavy, cumbersome machines to sleek andstreamlined racing cars. Airflow simulation using computational fluid dynamics has played a key role inthe development of vehicle shapes for boosting speedand performance. As a result, instead of cruising atslow speeds as they did in the early days, solar carstoday routinely travel at highway speeds.
Now constructing their eighth solar car, the
design team from the University of Waterloo has usedANSYS software extensively in studying vehicle aero-dynamics. The Midnight Sun IV through VIII solar carshave all been designed and thoroughly tested usingthe CFX-TASCflow product and now CFX-5.7 software. Using these tools, the team was able todevelop efficient body shapes and adaptable aerodynamic features that have significantly improvedvehicle competitiveness in recent races.
Designing a Record-BreakingSolar-Powered Car
ANSYS CFX simulation helps team from University ofWaterloo develop innovative aerodynamic vehicle.
By Greg Thompson, Aerodynamic Designer,
Midnight Sun Solar Race Car Project, University of Waterloo, Canada
In the 2003 American Solar Challenge, the Mid-
night Sun VII solar car won a third-place finish over arace from Chicago, IL, to Claremont, CA, and capturedthe world distance record for the longest drive by asolar-powered car. The aerodynamic performance ofthe car, coupled with many other components,allowed the team to travel 15,070 km around NorthAmerica over 40 days during August and September2004 to capture the world record.
Achieving the Perfect Balance
The best solar cars do not simply have the most effi-cient aerodynamic bodies but also achieve the perfectbalance between the many components comprisingthe vehicle. The aerodynamic shell interfaces withalmost every other system on the solar car, providing abacking for the solar array and an enclosure for thechassis, driver and internal workings of the car. Modern solar cars typically feature highly streamlinedbodies with a gentle curvature of the top surface,
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ANSYS Solutions
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Spring 2005







ANSYS CFX is an important tool in the aerodynamicdesign of the Midnight Sun solar car.
providing an optimized balance between a flat surfacefor the solar array and an aerodynamic overall vehicleform. Small teardrop-shaped canopies in the middle ofthe array provide visibility for the drivers, while stream-lined wheel fairings house the wheels and suspensioncomponents.
The Midnight Sun IV through VIII, in addition to
the original Midnight Sun I, solar cars have followedthese general design principles. These four genera-tions of cars from Waterloo have also distinguishedthemselves with elevated ground clearances to allowthe vehicle body to capture crosswinds and sail.Extensive si