Discussion Forum

time step

What is the reason why the convergence curve is peak shaped (up and down), and after a few hours, the calculation progress is only 4%? The time step is like this：range（0,0.001,0.01），range（0.01,0.03,0.1），range（0.1,0.3,1），range(1,1,20)s.The transient process I studied is approximately 20 seconds.Thank you.

6 Replies Last Post Mar 21, 2023, 11:49 a.m. EDT

Posted: 2 weeks ago

Based on the information you are providing I can assume that there must be a problem.

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com

Posted: 2 weeks ago

In case it isn't obvious, Edgar is suggesting that without looking at your model only the wildest guess is possible.

If your model contains proprietary elements, you may want to consider making a simpler model that exhibits the same sort of behavior. Indeed, putting together a model with simpler geometry and the same physics is often very helpful.

We need a "sticky" addressing "how do I ask a question that is likely to result in a helpful response?"

Posted: 2 weeks ago

We need a "sticky" addressing "how do I ask a question that is likely to result in a helpful response?"

Shouldn't that be something one learns at school and university in the first place? Not sure if any sticky would help. Well, I am really surprised how often complex questions are based on a null information, not only in this forum.

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com

Posted: 2 weeks ago

Hello Dave and Edgar,

As it were, for a while I have thought of writing a document that would suggest to users of this Discussion Forum ways of improving their chance of getting useful responses from other users.

One of the reasons I have not done so already is that I don't think I can do much better than this fantastic page which I remember reading back when I was a wee grad student. While it's not written specifically with COMSOL in mind, much of it is applicable to this forum anyways, and it's a fun read. I'll just point out that its author uses the term "hacker" to mean something other than what most people think of today when they hear that word.

Best,

Jeff

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Jeff Hiller

Posted: 2 weeks ago

Jeff

Well if you DID write something include the following

• No acronyms
• clearly explain the problem- well enough for those not in the immediate area
• Post your model if at all possible !!!
• Be sure to browse the application gallery if trying to get started

Interesting link, I will have a look at it.

I remember many occasions when grad students would ask for advice and want a short answer...and I would spend time working back to find out what the real problem was.

Posted: 2 weeks ago

The link that Jeff posted does contain very useful advice. However rather wordy and some parts not really applicable to Comsol questions.

Apparently the people who respond here are not as testy as those who haunt Linix forums.