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How to restrict the scale of calculation

Posted 5 mar 2013, 04:16 GMT-5 Parameters, Variables, & Functions, Studies & Solvers, Structural Mechanics Version 4.3a 5 Replies

Andre Müller
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Well, I'm interested in a model as attached. I'm using the Structural Mechanics Module in order to calculate a deformation at low temperature caused by different thermal expansion coefficients. Therefore I have two parameters to play with: the width of the top metallization and its height. But, I'm just interested in stress calculations (solid.sy, solid.sxy) relating to the centered point X shown in the attached figure as well (green). I set the point already in the model to make it selectable after the calculations.

My problem is, that the calculation will calculate everything and the calculation time will increase extremely (1s for one pair of parameters at the beginning and up to more than one minute at the end) due to the fact, that the whole solution for every pair of parameters and for the whole mesh is buffered in the memory. Concerning that matter the server will crash in most cases at 80 or 90 % of calculation.

Now my question:
Is it possible to restrict the scale of calculation, so that only the mentioned values (solid.sy, solid.sxy) at the point X will be (calculated and) buffered?

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5 Replies Last Post 6 mar 2013, 08:44 GMT-5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 5 mar 2013, 06:51 GMT-5
Hi

there should be some chekc box to get COMSOL to save the different solutions into different files (there was in 3.5a at least), or you should use Matlab.

On the other hand, are you sure you need that many points per variable, I suspect that you will get a rather smooth curve that you can easily (and precisely) interpolate, even with 3-4 per variable, no ?

Even if COMSOl gives precise results, there is no true reason to run more solver cases than strictly required, or ... do you have time to spare ?

--
Good luck
Ivar
Hi there should be some chekc box to get COMSOL to save the different solutions into different files (there was in 3.5a at least), or you should use Matlab. On the other hand, are you sure you need that many points per variable, I suspect that you will get a rather smooth curve that you can easily (and precisely) interpolate, even with 3-4 per variable, no ? Even if COMSOl gives precise results, there is no true reason to run more solver cases than strictly required, or ... do you have time to spare ? -- Good luck Ivar
Andre Müller
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Posted: 1 decade ago 5 mar 2013, 07:34 GMT-5
Thanks for your reply.

Well, I know about the option to save the different solutions into different files, but I thought that I have to open each file seperately to extract the calculated values and that would be to complex for 1600 solutions, isn't it?

I need 40 values per variable because the result is too complex to interpolate it as well as needed.

So, there is no possibility just to buffer one value per solution instead of buffering the whole solution?
Thanks for your reply. Well, I know about the option to save the different solutions into different files, but I thought that I have to open each file seperately to extract the calculated values and that would be to complex for 1600 solutions, isn't it? I need 40 values per variable because the result is too complex to interpolate it as well as needed. So, there is no possibility just to buffer one value per solution instead of buffering the whole solution?
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 6 mar 2013, 00:54 GMT-5
Hi

I believe you would have to use Matlab or Java then, but there might be others with better ideas.

perhaps in "batch mode" with "export to file" of a derived variable could work, but I have never tried that.
Still astonished that you need sch a mapping, but OK some models are more complex than what they seem at first ;)

--
Good luck
Ivar
Hi I believe you would have to use Matlab or Java then, but there might be others with better ideas. perhaps in "batch mode" with "export to file" of a derived variable could work, but I have never tried that. Still astonished that you need sch a mapping, but OK some models are more complex than what they seem at first ;) -- Good luck Ivar
Andre Müller
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Posted: 1 decade ago 6 mar 2013, 04:34 GMT-5
Hi,

thanks so far. After 4 days of waiting the simulation crashed at 95%, so I want to try the mentioned option to "save each solution as model file" which pops up by selecting "only last" for "Keep solutions in memory" inside of "Parameter sweep". For a first test I just used 4 values per parameter and the study finished successfully. But now I wonder where to find the solutions? Under results I only can take a look to the last solution and they also won't appear by changing the options of "Data set".

Thanks ;o)

EDIT: OK, I found them under "Job Configuration" -> "Parametric 1" -> "Save Model to File"
Hi, thanks so far. After 4 days of waiting the simulation crashed at 95%, so I want to try the mentioned option to "save each solution as model file" which pops up by selecting "only last" for "Keep solutions in memory" inside of "Parameter sweep". For a first test I just used 4 values per parameter and the study finished successfully. But now I wonder where to find the solutions? Under results I only can take a look to the last solution and they also won't appear by changing the options of "Data set". Thanks ;o) EDIT: OK, I found them under "Job Configuration" -> "Parametric 1" -> "Save Model to File"
Andre Müller
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Posted: 1 decade ago 6 mar 2013, 08:44 GMT-5
OK, I want to give a solution by myself for everyone who has the same problem.

I found the possibility to define probes (for boundaries and also points), where you can setup the coordinates and the expression which you want to calculate - exactly the thing I was looking for. Then you activate the option "only last" for "Keep solutions in memory" inside of "Parameter sweep". Now, calculation won't freeze and the calculated expressions (sxy, sy, ...) for the sweeping parameters will be added into a table while the calculation.

Instead of waiting 4 days without a successful finish I'm just waiting 3 and a half hours. Amazing!
OK, I want to give a solution by myself for everyone who has the same problem. I found the possibility to define probes (for boundaries and also points), where you can setup the coordinates and the expression which you want to calculate - exactly the thing I was looking for. Then you activate the option "only last" for "Keep solutions in memory" inside of "Parameter sweep". Now, calculation won't freeze and the calculated expressions (sxy, sy, ...) for the sweeping parameters will be added into a table while the calculation. Instead of waiting 4 days without a successful finish I'm just waiting 3 and a half hours. Amazing!

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