Menu

Discussion Forum

New Discussion
查找

Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

how to get rid of unrealistic offset in simulation

Posted 2015年6月22日 GMT-4 13:11 Acoustics & Vibrations Version 4.3 1 Reply

Daniel Atehortua
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hi everyone,

I am performing transient acoustic simulation runs in solid media (the sketch of the geometry is attached to this message) in order to assess sound wave interaction with different type of defects. To do so, I am integrating the sound pressure of the incident wave along a specific line (i. e. an edge) in every time step. The results looks like the "figure" archive attached to this message. The problem is that I am getting a strange offset value, which seems to be present any time the wave is reflected by a defect surface (in fact, it is a line as the simulation is 2D). I am sure the offset does not depend on mesh quality (I have tested several meshes).

Another thing that could be producing the offset might be related with convergence issues at some specific time steps. When the convergence is not good enough, the time dependent solver seems to jump, and I guess it could be producing the unwanted behaviour too.

Could you please tell me some ideas in order to get rid of it?? I will be really thankful.

Best Regards,

Dan

Attachments:

1 Reply Last Post 2015年7月29日 GMT-4 10:34
COMSOL Moderator

Hello Daniel Atehortua

Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.

If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.

Daniel Atehortua
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 2015年7月29日 GMT-4 10:34
Ok, I think I found the problem, if somebody else is interested on it.

By tightening up relative and absolute error (up to 1e-8), I have been able to reduce y-offset from 20 Vpp to around 1 Vpp. Of course, this is very time consuming and demands extremely high computational resources. Now, in order to reduce computational time, I have found that some boundary conditions require more computational effort, so I changed them and the computed time was significantly reduced. This is where one needs to be creative in order to keep model characteristics when doing those changes. Now my model runs like a charm!!!!

Best Regards,

Dan
Ok, I think I found the problem, if somebody else is interested on it. By tightening up relative and absolute error (up to 1e-8), I have been able to reduce y-offset from 20 Vpp to around 1 Vpp. Of course, this is very time consuming and demands extremely high computational resources. Now, in order to reduce computational time, I have found that some boundary conditions require more computational effort, so I changed them and the computed time was significantly reduced. This is where one needs to be creative in order to keep model characteristics when doing those changes. Now my model runs like a charm!!!! Best Regards, Dan

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