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Performing Analysis including Fans and Utilizing Results in Many Areas


A fan is considered to be relatively unsuitable for thermo-fluid analysis among electronics components. Because a fan is a moving component, flow around the fan is normally extremely complicated. We interviewed a staff of ORIENTAL MOTOR CO., LTD. (hereinafter, Oriental Motor) about their present status of CFD (Computational Fluid Dynamics) analysis and designing case studies of fans, and how to effectively utilize simulation results. The company is known for fan motors used in specialized products such as "super computers".

Takahiro Ito
TM department
Chief researcher, Ph.D. (Engineering)

First-ever Automatic Meshing of Unstructured Grids

  In this situation, Mr. Ito came across "SC/Tetra" developed by Software Cradle, a thermo-fluid analysis software with unstructured grids. When he used the software for the first time, he was quite impressed by the way it generated smooth mesh automatically, without much preparation labor. Since no other set of analysis software came with a mesher that generates unstructured mesh automatically at that time, he decided to adopt SC/Tetra.

  With this software, it took only an hour to complete meshing once the boundary conditions and rotating regions were set for a CAD model. Also, the calculation itself did not take longer than two hours.

  Analysis conditions can be changed easily, even automatically, to perform analyses for different configurations. Other than fans Mr. Ito is dealing with, particular conditions such as combustion or chemical reaction can be also considered with the software.

New Inspiration through Simulations

  At present, they are performing analyses using SC/Tetra while making prototypes of new fans. They measure the P-Q characteristics of fans created by Rapid Proto Typing with a dedicated device, and confirm the characteristic differences through simulations. Then, the level and type of noise are analyzed with a special microphone in an anechoic chamber, and the data is used to reconsider the fan shape.

  "An advantage of a simulation is that we can rethink our belief about a flow pattern." says Mr. Ito. He has experienced that a comparison between CFD simulations and experimental results brings new ideas for a better product.

Fig.3 "Thermal design of electronic devices through CradleViewer"

Necessity to Learn How to Get Along with Simulation

  Meanwhile, a thermo-fluid analysis by its nature causes certain errors because of uncertainties: a numerical scheme usually gives an approximate solution, and the complete modeling of an actual product or a phenomenon is impossible. Still, simulations are considerably effective to reduce fatal design errors. Mr. Ito says "One of the great advantages of utilizing simulation software is to spare valuable time to address new challenges by reducing production rework from design errors." However, he is still struggling to make related departments understand these advantages of CFD software products. For instance, circuit design engineers determine various specs like a voltage by fractions. Therefore, they tend to believe the exact value of heat should be output once the conditions are determined. However, thermal issues are "hard to predict" for engineers dealing with heat problems. Mr. Ito says "It's like a perception gap between digital and analog ways of thinking." Even though design engineers cannot predict the exact temperature, they can fully avoid production reworks through prior simulations. He hopes that more engineers will understand the characteristics of CFD analysis and take full advantage of simulations.

  Based on these experiences, Mr. Ito published "Thermal design for electronics through CradleViewer" (Fig.3). The book is filled with practical knowhow on thermo-fluid analysis, and the accompanied CD-ROM helps users learn the practical thermal design for electronic devices including fans (Fig.4). He wrote this book to allow general engineers (not CFD experts) to visualize the flow in a way closer to the real flow. Also, design engineers can easily try dynamic designs with simulations, and create a prototype of a new product without time and money. Furthermore, simulations can help engineers narrow down their design ideas. For instance, proximity to a part generating high amount of heat can cause crucial errors in the layout of electronic parts. Here, such crucial errors can be predicted by performing a simulation in advance. Simulations are absolutely necessary for eliminating preventable design mistakes.


Fig. 4 Example of CFD analysis for electronic devices Arrows indicate the air flow.
​Temperature rises from blue to red.

User-friendly Access to the Simulation Results

 "CradleViewer" is a free software which enables users to see calculation results of SC/Tetra and "HEAT Designer" (thermo-fluid analysis software designated for electronics) provided by Software Cradle. Users can easily see images and animations in desired angles and scales. Now, analysis results can be confirmed under environments other than specified computers in which the analysis software is installed. A specific visual that is saved in SC/Tetra can be reproduced just by loading a file into CradleViewer.

  This software product also encourages communication between different departments. If you need to explain the necessity of expensive components for a thermal management, for example, the explanation only in words may not be persuasive enough to a person from a purchasing department. Here, if you show a simulation result, you will immediately make the person understand the "necessity of expensive components because a prominent temperature rise is predictable." Otherwise, he/she may give you the information of much better components. You can also explain people at assembly lines the necessity of special consideration before assembling parts of a specific position to avoid thermal problems based on the simulation results.

Acoustic Simulation: Future Challenge

  Acoustic simulation is their next target. Since the simulation requires even more detailed mesh than the analysis of heat or flow only, the calculation requires a considerably long time even with a super computer. It is even more difficult to perform the simulation with a normal, desktop computer. Now they are looking for other ways to achieve the acoustic simulation in collaboration with universities. Mr. Ito hopes, "If some index related to the sound is formulated, calculations may be performed with a normal computer with a basic specification. If this happens, it would bring innovation to a wide range of areas including electronics."

  Mr. Ito admits, "Experiences with failure are crucial for the development of a new product."

  Meanwhile, the good use of simulation tools will reduce production reworks and will provide adequate time for design engineers to perform constructive analyses. It would also benefit the engineers in utilizing the results in many other applications. He concludes that a better understanding about the effectiveness of the analysis tool and the full utilization of the tool are really important.

*All product and service names mentioned are registered trademarks or trademarks of their respective companies.
*Contents and specifications of products are as of May 16, 2011 and subject to change without notice. We shall not be held liable for any errors in figures and pictures, or any typographical errors.

Company Details


Founded 1950
Description of Business Development, manufacture and sale of small precision motors and electronic circuits for motion control
President Yoshio Kuraishi
Headquarters TOKYO
Capital 4 billion Yen



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