Menu

Discussion Forum

New Discussion
Filtrer

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.

Time range crashes simulation

Posted 28 janv. 2021, 14:00 UTC−5 Fluid & Heat, Computational Fluid Dynamics (CFD) Version 5.5 4 Replies

HB
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

I am running a CFD timde-dependent simulation using the mixture model. When I run the simulation with a time range t=0-5s the simulation runs well. However, when I run the simulation with the exact same setup with a time range t=0-10s, the simulation crashes almost immediately (t=4.764e-7s).

I was wondering what could be causing this behavior and how I could fix it.

Thanks in advance for any help. Humberto

4 Replies Last Post 28 janv. 2021, 14:31 UTC−5
Robert Koslover Certified Consultant
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 4 years ago 28 janv. 2021, 14:17 UTC−5

I would guess (just a guess) this relates to the time stepping process. Are you setting the time step sizes or are you allowing the software to do it? I suggest you pay close attention to that. There are many other possible problems, however. If you can't find the cause of the problem, I suggest you post your model to the forum so others can see the details.

-------------------
Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
I would guess (just a guess) this relates to the time stepping process. Are *you* setting the time step sizes or are you allowing the software to do it? I suggest you pay close attention to that. There are many other possible problems, however. If you can't find the cause of the problem, I suggest you post your model to the forum so others can see the details.
HB
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 4 years ago 28 janv. 2021, 14:22 UTC−5

Hi, Robert. Thanks for your reply.

I am using the "Free" option in the BDF method and an automatic maximum step constraint.

Hi, Robert. Thanks for your reply. I am using the "Free" option in the BDF method and an automatic maximum step constraint.
Robert Koslover Certified Consultant
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 4 years ago 28 janv. 2021, 14:29 UTC−5

I am using the "Free" option in the BDF method and an automatic maximum step constraint.

Yup. Consider something less free. Maybe even "strict." You can make it a bit more free later, maybe, once you get it to actually start executing.

-------------------
Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
>I am using the "Free" option in the BDF method and an automatic maximum step constraint. Yup. Consider something less free. Maybe even "strict." You can make it a bit more free later, maybe, once you get it to actually start executing.
Jeff Hiller COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 4 years ago 28 janv. 2021, 14:31 UTC−5

Indeed, like Robert hints at above, the automatic time stepping algorithm is the very likely source of the change in behavior when you change the final time. See my colleague Henrik's post in this thread, and this Knowledge Base entry.

Best,

Jeff

-------------------
Jeff Hiller
Indeed, like Robert hints at above, the automatic time stepping algorithm is the very likely source of the change in behavior when you change the final time. See my colleague Henrik's post in [this thread](https://www.comsol.com/forum/thread/108101/time-dependent-temperature?last=2016-03-30T05:33:04Z), and this [Knowledge Base entry](https://www.comsol.com/support/knowledgebase/1254). Best, Jeff

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