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Tokai University
Students Take the Lead in Simulating Solar Car Aerodynamics



Tokai Challenger

The Solar Car Team at the Tokai University Student Project Center (Kanagawa, Japan) has to be considered one of the premier student-led solar car design teams in the world after winning back to back World Solar Challenge races (2009 and 2011) in Australia. A critical aspect of successful vehicle design is minimizing aerodynamical drag since one major goal is to achieve high speeds while using minimal energy. The Tokai student-led team used Computational Fluid Dynamics (CFD) simulations to optimize the vehicle geometry. In particular they used Software Cradle SC/Tetra CFD Software for the simulations. Following are highlights from an interview with the Tokai team that discussed the educational advantages and usability of SC/Tetra in this challenging environment. 

Why SC/Tetra is so Good

 According to Dr. Fukuda, the advantages of SC/Tetra are its ease of operation and high accuracy. "The most important part in fluid dynamics simulation is to generate the mesh accurately". This is accomplished quite easily using the automatic mesh generation capabilities in SC/Tetra. It reduces the stress of mesh generation and facilitates evaluation of more geometry variations.


 About accuracy, Dr. Kimura said, "It [SC/Tetra] never goes wide of the mark. When we modify part of the geometry, it shows up in the result. With some other simulation tools, it often happens that when we tweak some parameters, the result comes out the opposite of the facts we know. SC/Tetra simulates this sort of relative changes correctly; we can trust it."


Tokai Challenger

Usability from an Educational Perspective

 As a whole, SC/Tetra is well received by the students. They can clearly see how design changes affect the air flow around the vehicle. Visualizing the impact of their design changes creates excitement.


 Dr. Fukuda also emphasizes the educational advantages of SC/Tetra software. "Simulations can be performed in a relatively short time frame using SC/Tetra. This makes it suitable for classroom use". The software is appreciated not only by engineering students but also by industrial design students. More and more, industrial designers are expected to pay attention to the functional aspects of products and not just the aesthetics. For example, in automotive design, a design that is visually attractive but has low aerodynamic performance may not be accepted. Dr. Kimura says, "There are some students who want to pursue their careers in car design. For them, the process of designing and getting feedback from functional computational simulations presents an opportunity to get the feel of their future work".

Continuing on the Winning Track

 The Solar Car Team is now in the middle of the design process for their entry in World Solar Challenge 2013 where they aim for their third consecutive win. Competition regulations have changed drastically since the last competition, requiring major modifications to the car body. The regulation changes are aimed at increasing safety and practicality. For example, the new vehicle configuration is a four wheel vehicle instead of a tricycle. The driving position must now be similar to that used in a conventional passenger car. The overall size of the vehicle is smaller. In sum, these new requirements suggest inferior aerodynamic performance compared to past solar cars. Consequently, the contributions from computational simulations become even more critical.


 The Australian World Solar Challenge has been held since 1987 and is the most highly regarded solar race. In 2011 thirty seven teams from twenty nations and territories participated. The contesting cars run approximately 3000 km (1864 miles) across the country with 700 km (435 miles) being on highways. This amounts to about five days on the highways. When the Tokai Challenger won in 2011, it completed the route in 32 hours and 45 minutes averaging just over 90 km/h (56 mph).


 In contrast, Solar Challenge South Africa is a FIA (International Automobile Federation) certified race, which is open to a variety of alternative fueled vehicles including, solar, electric and hybrid electric powered cars. While the South Africa race has fewer participants, it is much more difficult. It is the longest race covering nearly 5000 km (3107 miles) with altitudes as high as 2000 m (6562 ft). This race includes tight turns, traffic lights, and a lot of traffic on the open roads. In 2012 the Tokai vehicle completed the route in 71 hours and 13 minutes over a five day period.


 Successfully competing in either solar race requires an accomplished support team. Voltages and temperatures of the solar cells are monitored at all times. This data is sent to the command and control car via radio waves by a student-developed telemetry system. Weather information is obtained from the geostationary satellite "Himawari" and converted into information the team can use for the race. Solar radiation intensities are acquired from satellite data using "T-SEED", a system developed by the Center for Environmental Remote Sensing at Chiba University and the Tokai University Research & Information Center.


 Solar car races require design, development, and implementation of a broad range of technologies. The entire technical team must be fully engaged. These races challenge the comprehensive strength of the participants. From an educational viewpoint, the students develop technical skills, learn to work as a team, and often take leadership roles. This is most apparent during the aerodynamic simulation stage of the initial design, the first step toward improving the driving speed. Currently, simulations are under way for the next Challenge in Australia. The world anxiously awaits the next entry from the Tokai University Solar Car Team.

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*Contents and specifications of products are as of December 1, 2012 and subject to change without notice. We shall not be held liable for any errors in figures and pictures, or any typographical errors.

Institute Details

Tokai University Solar Car Team

Tokai University - Solar Car Team

1991 Solar Car Project launched at Tokai University
1996 Hideki Kimura Laboratory begins design of a high performance solar car as a member of the solar car team
2006 Program restructured to become the Light Power Project's Solar Car Team at the Tokai University Student Project Center
Professor Dr. Hideki Kimura (Top left in picture) Department of Electrical and Electronic Engineering, School of Engineering
Lecturer Kota Fukuda, Dr. Eng. (Top right in picture) Department of Aeronautics and Astronautics, School of Engineering
Ryuji Otsuka (Bottom left in picture) Sophomore in Department of Prime Mover Engineering, School of Engineering



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