2D Axisymmetric and 3D Model Differences - Metal Plate in Air Domain
Posted Dec 18, 2023, 2:08 p.m. EST Structural & Acoustics, Acoustics & Vibrations, Results & Visualization Version 6.0 6 Replies
Please login with a confirmed email address before reporting spam
Hello. I am working to model an aluminum plate excited by an impulse excitation at its center and surrounded on top by an infinite air domain. I have successfully modeled this case using 2D Axisymmetric geometry, see attached file, and the simulated plate acceleration and air acoustic pressure at points defined in the model match experimental measurements. I am now trying to model this same setup using a 3-dimensional model and do not seem to get the same results as the 2D Axisymmetric model. I have placed an impulse excitation at the plate's center, and the plate seems to be vibrating symmetrically as expected. The acoustic pressure measurements in the air seem to arrive much earlier than they did in the 2D Axisymmetric model and look to be very different. I cannot figure out why. It also seems that the acoustic pressure measurements are not symmetric, measuring different at different points above the plate that are the same distance from the source. I have attached the 2D Axisymmetric file and the 3D file if that will help diagnose the problem. In these models I have table results for the data I am trying to match the simulation to. I appreiate your insight! Thank you in advance!
Attachments:
Please login with a confirmed email address before reporting spam
Hi Allison,
a few observations:
the 3D mesh is much coarser than the 2D mesh. Are you still sampling the field at 6 elements per wavelength?
there is no PML in the 3D model, this may explain deviations in the measured amplitudes due to reflections.
Cheers Edgar
-------------------Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Please login with a confirmed email address before reporting spam
Hi Edgar,
Thank you so much for looking over my models! I really appreciate it!
You are correct that I have no PML in the 3D model. I removed it to make sure the PML was not the cause for the early wave arrival times in the air domain. I have since updated my geometry to add the PML back into the 3D model so that the 2D and 3D geometries will match.
I will look closer into the meshing. The 6 elements per wavelength that I used for the 2D model mesh seemed to work really well and give accurate results. I tried making the mesh for the 2D model more coarse, and found similar acoustic pressure trends to the 3D model, so it looks like the coarse mesh may be the cause of my problems. Do you have any tips for designing a 3D mesh that is fine enough to give accurate results, but won't weigh down the run time of the model too much?
Best, Allison
Please login with a confirmed email address before reporting spam
Hi Allison,
yes I know the pain. I am doing a lot of acoustics and there is no way around sufficient meshing. You can try to make the air space as small as possible and often I am using linear discretization instead of the default quadratic. That saves a lot of computational costs. Often the results are accurate enough. In case you can use frequency domain you could try the boundary element method, which avoids having to mesh the air domain, but needs 4th order discretization on the boundaries.
Cheers Edgar
-------------------Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Please login with a confirmed email address before reporting spam
One more idea: exploit any symmetries. I only took a quick look at your file but it gave me the impression of having planes of symmetry. Alas that approach will only work if you are not working your way towards a system with no symmetries - and I am guessing that is where you are headed.
Jeff
-------------------Jeff Hiller
Please login with a confirmed email address before reporting spam
Hi Edgar,
That is really helpful advice. I appreciate it. I am a student who just started learning Comsol, so I am not familiar with linear discretization as opposed to quadratic. I will look into that further as any chance of lowering computation costs while maintaining accuracy will be best. I am hoping to stay in the time domain as I want to limit how many plate edge reflections are included in my solution, so I am not sure the frequency domain will work for this particular simulation, but I will keep it in mind for future simulations!
- Allison
Hi Jeff,
I appreciate your advice as well. I am working with a symmetric model to ensure everything is working correctly in the simulation, then will be moving away from a system with symmetries. Unfortunately it doesn't look like I'll be able to exploit any symmetries as I will be moving the source and sensors to no longer by symmetric in any direction. For troubleshooting, I will try and exploit some of my symmetries to make sure my 3D model has a fine enough mesh to give accurate results.
- Allison
Please login with a confirmed email address before reporting spam
Hi Allison,
you have a good strategy. From the simple to the complex and continuous verification. That is how it should be done.
Good luck Edgar
-------------------Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Reply
Please read the discussion forum rules before posting.
Discussion Forum Rules and Guidelines
The goal of COMSOL Access is to provide a forum for you to communicate effectively with COMSOL as well as your colleagues within the multiphysics simulation community. This involves providing you with access to technical support and downloads of the latest {:comsol} software releases, as well as the ability to share your comments and work with other users of the {:comsol} software through forums such as the blog, discussion forum, and Application Exchange. In order to make this an efficient and pleasant experience for you and other members of COMSOL Access, we ask that you follow a few rules and guidelines.
When registering for COMSOL Access, you agree to provide your complete and truthful information for all fields requested on your COMSOL Access account registration page. You also agree to maintain the accuracy of all information associated with you on your COMSOL Access account. You agree to maintain your COMSOL Access account for use solely by you, not to share your username and password with anyone else, and to take appropriate precautions to restrict access to your username and password from others. Furthermore, you agree not to submit any information relating to your employer through your COMSOL Access account without your employer’s authorization. Should you use a COMSOL Access account associated with an employer, you agree to immediately discontinue using that account upon termination of that employment.
The moderators of the forums will remove any generally objectionable material as quickly as possible. You acknowledge that all posts made to these forums express the views and opinions of the author and not the administrators, moderators, or webmaster (except for posts by these people). Hence, they will not be held liable.
You agree not to post or link to any material that is abusive, obscene, vulgar, slanderous, hateful, threatening, sexually oriented, or that infringes upon or violates any third-party rights or any other material that may violate any applicable laws. You agree that you will not otherwise use your COMSOL Access account to violate or to assist anyone in violating any law. Engaging in any activity in violation of these COMSOL Access rules and guidelines may lead to you being immediately and permanently banned from COMSOL Access. The IP address of all posts is recorded to aid in enforcing these conditions. You agree that the webmaster, administrator, and moderators of the forums have the right to remove, move, or close any topic at any time as they see fit. As a user of COMSOL Access, you agree to any information you have entered into any of the forums being stored in a database.
You agree that you will not use your COMSOL Access account in violation of any applicable export control laws. You represent and warrant that you are not subject to any comprehensive sanction or embargo by the U.S. or any other country, nor are you identified on any list maintained by the U.S. government that identifies persons for which the U.S. maintains restrictions. Further, you represent and warrant that you are not subject to any restriction on the receipt of technology or products under the export control laws of the U.S. or any other country.
Basic Rules
- Flaming: Do not post any messages that harass, insult, belittle, threaten, or flame another member or guest. Debates are fine, but argue with the point, not the person.
- Trolling: Do not post with the purpose of starting a dispute. Note that a person disagreeing with your opinion is not considered trolling; keep it civil, even if you are sure that the other person is wrong. Anything seen as trolling will result in you being banned.
- Spamming: Posts without content or containing nonsense waste space and everyone's time. Spam will be removed from the forum.
- Offensive Posts, Links or Images: Do not use profanity, racial, ethnic, religious, or other slurs or any other offensive material.
- Advertising: Posting of advertisements for products or services, links to auctions, affiliate links, links to promote websites, and so forth is not allowed.
- Disclosure of Personal Information: Do not disclose any other member's email, real name, address, phone number, IP address, or other personal information. This includes posting contents of emails and private messages without the sender's consent. Do not bring personal disputes into the forums. Bans and warnings issued to other users are considered personal information.
- Misleading Titles: The subject line of the post should be as informative as possible about the content of the post. This also reduces the amount of duplicate posts.
- Thread Hijacking: Taking a thread off-topic to pursue one's own agenda is not permitted.
- Piracy: Do not upload, post, email, transmit, or otherwise make available any content that infringes upon any patent, trademark, trade secret, copyright, or other proprietary rights ("Rights") of any party. This includes COMSOL model files created by a forged or illegitimate license.
- Honesty: Users must provide truthful information in creating their COMSOL Access account.
These rules are subject to change. The moderators reserve the right to remove, edit, or move posts at their discretion. The COMSOL Access administrators will reserve the right to permanently remove a user account without notice if any of the rules are not followed. Particular services accessible with your COMSOL Access account may be subject to additional rules. You agree to comply with all rules applicable to each service you access through your COMSOL Access account.
Posting Guidelines
When posting, understand that you are trying to communicate with other people. Although many COMSOL Access members are not fluent in English, the official language of this forum is English.
Here are some important guidelines of language:
- Write in English.
- If you are familiar with LaTeX, please use this to write mathematical equations.
- Always do a quick check for spelling/grammar mistakes.
- Format your post in a legible manner. Use the Preview button often.
- Be concise and articulate as much as possible.
- Use the Enter key to create paragraphs.
- Capitalize correctly. It is difficult to read posts that are written entirely in uppercase or lowercase.
- Use correct punctuation. Avoid run-on sentences.
- Try to avoid using “text speak”, “net speak”, or slang. The purpose of language is to be understood.
- Never invent acronyms and use as few acronyms as possible. For example, write "COMSOL Multiphysics" and not "CMP".
- Review your post before publishing it. Try to catch typos.
- Please check to see if a topic has already been posted. Do not post multiple threads on the same topic.
Disclaimer
By submitting content to the forums, you hereby grant COMSOL a nonexclusive, royalty-free, perpetual, worldwide, and unrestricted license to reproduce, publicly display, publicly distribute, and prepare derivative works of the content. COMSOL hereby grants you a license to copy and/or use content from the forums solely for your own internal purposes. COMSOL provides the forum service for the benefit of our users to share content with the community. All content is provided "as is" without warranty of any kind, express or implied, including without limitation, warranties of merchantability, noninfringement, design, operation, and fitness for a particular purpose, and the entire risk as to the quality and performance of the programs is with you.
Neither COMSOL, the authors, nor the copyright owners of submitted materials warrant that the programs will be error-free, uninterrupted, virus-free, secure, and suitable for your needs, produce specific results, or that errors or failures will be corrected. Comments on supplied content should be sent to the author or copyright owner through the tools provided in the forums.
Please log in to post a reply.
Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.
Suggested Content
- FORUM Axisymmetric permanent magnet and ferromagnetic shield simulation model and plots
- BLOG How to Choose Between Boundary Conditions for Coil Modeling
- KNOWLEDGE BASE Failed to respect boundary element on geometry face
- BLOG Analyzing Kelvin Probe Designs with COMSOL Multiphysics®
- FORUM Differences in the results of the same model in 3D and 2D.