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Welcome to the Inside Track with ARC. The Auto Research Center is a specialized research facility serving the motorsport, automotive production, commercial, government and bicycle industries. The ARC global headquarters is located in Indianapolis, Indiana which hosts a 50% scale wind tunnel, 7-post, drivetrain test rig, bicycle test facility and CFD cluster center. ARC offers a wide range of solution type packages to further speed and efficiency.
THE IMPACT OF SCALE MODEL SIZE ON RESULTS
When it comes to differences in scale model sizes, the aerodynamic results are always a talking point. To examine the impact of scale sizes further, ARC conducted a CFD study, along with wind tunnel testing between 40 % and 50% Indycar scale models. By using the ELEMENTS CFD package, which has been validated with real wind tunnel and track testing, some interesting results were produced.
When it comes to scale testing, there are two significant aspects associated that must be evaluated in order to obtain reliable results. Flow similarity and accurate geometry representation. Flow similarity must be maintained around a scale model and in part is achieved by Mach number and Reynolds Number matching. Get the flow right and you get closer to accurately simulating real-world conditions.
In theory, increasing the model size does produce better resolution with the Reynolds effect issues. However, as with the operating speeds, a wind tunnel is limited by the size of the working section. Due to size limitations, blockage can become another issue.
The study found the difference in absolute lift and drag coefficients were within 3 counts between 40% and 50% scale models in ARC's wind tunnel. When development part changes were made, there was absolutely no change in delta between the model scales!
The key takeaway is, while the study shows overall results are impacted by scale size, the part change delta is the same between a 50% model as compared to a 40% model, particularly when conducting setup and body configuration changes in high downforce (worst case) configurations.
To learn more about ARC's offerings for the Motorsports Industry, visit the ARC website
ELEMENTS CFD V2.2.0 LAUNCHES
Streamline Solutions, the joint venture between ARC and ENGYS Ltd, is delighted to announce the release v2.2.0 of ELEMENTS, an open-source based CFD software suite for vehicle design applications. The product combines two simulation tools: a dedicated wizard type interface for modelling external vehicle aerodynamics in a virtual wind tunnel, and a general purpose CFD interface for solving other vehicle design applications, such as: UHMT, HVAC, in-cabin flows, aeroacoustics, soiling, etc.
 Enhancements delivered with this new version of ELEMENTS include, but are not limited to:
- Improved DES solver robustness with advanced velocity filters
- Improved simulation best practices for external aerodynamics of SUV, squareback and stock vehicle types
- New import functions for OBJ, STEP and IGES geometry data
- New turbulent atmospheric inlet boundary condition
- Improved features for data visualization and post-processing
- Up-to-date documentation, all accessible via the Help menu in the GUI
Read the full release details at: http://www.arcindy.com/streamlie-solutions-cfd-elements-automotive-v2-2-0.news
To learn more about ELEMENTS, visit the ARC website, call 317-291-8600 or email at sales@arcindy.com
CHINA EXPANSION MOMENTUM CONTINUES WITH YIDUO INFORMATION TECHNOLOGY BECOMING ELEMENTS CFD RESELLER
ELEMENTS CFD software suite, designed exclusively for Automotive purposes, has fully entered the Chinese market with the addition of Yiduo Information Technology Co., Ltd as an official reseller. Yiduo, based in Shanghai, was founded by Qi Li who was formerly a VP at the largest software reseller company in China. Yiduo is excited to offer ELEMENTS CFD, as a part of their already large lineup of automotive, naval and design CAE platform development packages.
 Streamline Solutions, the partnership between ARC and ENGYS Ltd is the developer of ELEMENTS CFD, which includes the most accurate Adjoint simulation publicly available in the world. This partnership provides a unique benefit to the ELEMENTS CFD software suite. ENGYS Ltd is composed of personnel who participated in writing the core of OpenFOAM™ source code and continue advanced software development beyond what is publicly available, while ARC provides the validation tools and design experience to ensure top correlation between CFD and actual real world results.
For those in the Chinese market, interested in purchasing ELEMENTS CFD, Yiduo Information Technology Co., Ltd can be contacted via their website at: http://www.yiduo-tech.com ELEMENTS Product Manager, Rui Xu, xurui@yiduo-tech.com, +86 136 6156 0176 (mobile) will be happy to explain all benefits and a full training package can be included.
ARC's DIRECTOR OF ANALYTICS, JEAN-MICHEL ESCLAFER DE LA RODE, TO BE GUEST SPEAKER AT ATVWT IN SEPTEMBER
The 2016 International Symposium Automotive Wind Tunnel Applications, main topic of discussion this year will be CFD and its relation to wind tunnel testing. Thus, ARC was a perfect fit for the conference, with Jean-Michel Esclafer de La Rode to present a validation approach of a virtual wind tunnel using the ELEMENTS CFD package. Jean-Michel will be joining guest speakers from around the world to participate in this rapidly growing conference. The conference will take place on September 6-7 in Chongqing, China.
ARC and the ELEMENTS CFD software package will also be on display at the conference. Yi Duo, the Chinese reseller of ELEMENTS will have a booth to answer all questions about the CFD package designed for Automotive purposes. Read more about the conference at the conference website here.
STUDY ON SHORT VERSUS LONG NOSE TRACTORS REVEALING SOME SURPRISING RESULTS
The often discussed differences between tractors around the world are being put to the test at ARC in an aerodynamic study using ELEMENTS CFD software suite. Past findings indicated putting a long nose on a short tractor design didn't automatically mean a reduction in aerodynamic drag. Results so far have been very interesting, shedding light onto benefits for commercial operators and will impact the future of how tractors are designed.
Using identical trailers and tractor-trailer gap, the long-nose design produced nearly 8% less drag at highway speeds! A sample from our CFD study shows the longer nose design generating noticeably less drag (yellow regions) on the frontal profile, however the short nose cab is also generating more thrust at the front from the high outboard acceleration (blue regions).
One of the key fundamental differences we see with long nose cabs is the opportunity or amount of room to significantly improve the front wheel wake before it reaches the cab rear wheels and trailer. An example of this can be seen in the total pressure iso surfaces (red turbulent regions). You can visualize the effect the wake originating from the front wheel has on the rest of the truck.
So far we have observed that, in general, a long-nose cab can substantially reduce the overall fuel consumption and thus operating costs for their users. But is this always the case? Stay tuned for further insights into our comprehensive study. Interested in more of what ARC does for the commercial industry?
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TECH ZONE
What role do aerodynamics play in electric bus range?
Perhaps surprisingly aerodynamics does play a large role in extending electric bus range. With electric buses becoming more popular in cities around the world, a focus on battery range has really come into focus. It is often said that buses tend to operate a road speed too low for aerodynamics to play a factor. While it's true that aerodynamics become much more prevalent at higher speeds, aerodynamics is more than just reducing drag with sleek designs.
The real aerodynamic gain comes from HVAC design. For traditional city driving, especially in hot or cold weather environments, the batteries are put under additional strain by having the temperatures in and around them fluctuate. Having cooling and heating units for batteries, again increases the load required by batteries. A proper aerodynamically designed cooling/heating ductwork system will greatly improve battery performance. Using a CFD code like Adjoint, is the optimal way to reach HVAC targets faster.
TECH ZONE is an additional area of our newsletter where each month a customer question will be answered by the related expert at ARC. Please send in any questions you might have, from wind tunnel test instrumentation, CFD workings, to tuning your shocks.
Ask your questions at techzone@arcindy.com
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