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Nihon Automobile College (NATS)
CFD Tools Help NATS Team in the Student Formula Japan by Improving Vehicle Performance

NATS entered and placed seventh in just their fourth appearance in SFJ 2013, where participating teams compete on vehicle design, performance, mass production cost estimation, and presentation skills. A major technical improvement was the use of SC/Tetra to conduct fluid analysis that resulted in enhanced vehicle drivability and production of professional quality presentation materials.

Evaluating the Aerodynamic and Motion Performance Using SC/Tetra

 Mr. Murakami’s team used SC/Tetra to analyze the surge tank and aerodynamic performance of the vehicle. The surge tank stores and supplies air to each cylinder of the engine. They analyzed the previous vehicle model, FFN-02, which competed in SFJ 2011, and found that the inlet flow was non-uniform. After thorough evaluation, Mr. Murakami’s team enlarged the tank diameter from 70 to 90mm. Also, they changed the orientation of the intake manifold, which connects the surge tank to the engine, such that it was in line with the inlet and restrictor. Previously, the surge tank was at a right angle to the inlet and restrictor. As a result, the engine received a uniform inlet flow, as shown in Figure 1, and 2.8m/s higher maximum velocity.

Figure 1: Analysis of a surge tank

  Mr. Murakami explains that their team used CFD after the 2012 tournament to improve the aerodynamic performance of their vehicles, although they struggled to generate reliable results at the beginning. “We used to export CAD data in a format that can be read on a CFD tool and then surface-wrap the model before using it for the analysis. The trouble was that the original CAD data was not translated perfectly, ending up with gaps and layered faces which had to be manually repaired. Before SC/Tetra Version 10 was released, we had to simplify the original CAD data each time, but since Version 10 we can now accurately import the geometry CATIA files directly. This was a great improvement compared to before,” says Mr. Murakami.

Figure 2: Comparison of vehicles with and without
​a diffuser

 Aerodynamic analysis proved to be effective. For example, when Mr. Murakami’s team designed the vehicle’s underbody diffuser shape, they designed the diffuser to increase the down force by letting the air under the car to accelerate and reduce the pressure (Figure 2). They also achieved a reduction in turbulence by raising the shape of the side pod and minimizing the air blowing against the wheels.

Tutorials Providing Increased Expertise in Software Operation

 One of the benefits of using SC/Tetra is its user-friendliness. Mr. Murakami recalls that he “received a lot of help from the tutorials.” After Mr. Hayashi’s training for using the software and reading the tutorials, Mr. Murakami became comfortable using the functions in the software. “Our objective was to estimate CD*1 and CL*2 values so I looked at the tutorials with similar objectives and made calculations according to these examples,” says Mr. Murakami. The user interface was also easy to comprehend, especially for modeling and generating the mesh. According to Mr. Murakami, the tutorials “clearly indicated user actions needed for the next step.” He says that he could solve most of the problems on his own, by simply reading the Help sections and applying the suggested solutions.

 Mr. Hayashi says that he was satisfied with Cradle’s prompt technical support for the inquiries he made about the manifold analysis. Mr. Murakami further notes that performing CFD analysis enabled him to visualize phenomena that cannot be easily observed in experiments. “I was fascinated to visually learn that even a slight change to the cowl dramatically affected the flow,” says Mr. Murakami. His interest in fluid dynamics has increased considerably since he started using CFD.

*1 Abbreviation for Coefficient of Drag
*2 Abbreviation for Coefficient of Lift

Using SC/Tetra for More Accurate Analysis

 Although Mr. Murakami’s team has primarily used CFD to visualize the effects of changes to models, they are planning to set numerical goals and use the analysis to determine the best design that meets the goal. They are also expecting to undertake investigations combining CFD analysis with other tools, including the Chassis Dynamometer that measures vehicle performance and power output. “As we begin to do this, we would love to consult the Cradle technical staff about how to model this system,” says Mr. Hayashi with anticipation.

 The NATS campus is furnished with a 1/24 scale wind tunnel. Producing a prototype can be done much more easily today than years ago with the advent of such tools as 3D printers. NATS 3D printing offers many opportunities for building accurate physical models quickly. NATS also believes that modeling of the cowl can be further improved by combining wind tunnel experiments with CFD analysis.

 To summarize, NATS is an excellent case example where applying SC/Tetra has helped them achieve a better learning environment and tournament results. The software is expected to provide extensive and sustainable support for future students.

*All product and service names mentioned are registered trademarks or trademarks of their respective companies.
*Contents and specifications of products are as of January 31, 2014 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


Nihon Automobile College (NATS)
Established 1989
Founder Nichiei Academy (educational foundation)
Type of school Technical college
Location Narita-shi, Chiba, Japan
Courses provided Mechanics, Customization, Motorsports, and Research



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