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Memory not released in COMSOL 3.5a

Posted Apr 21, 2010, 12:24 a.m. EDT 5 Replies

Laith Hurmez
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Hi,

I'm trying to solve the lubrication equation (time dependent 4th order nonlinear PDE solved as a system of 2 nonlinear PDEs) using the General equation form in COMSOL 3.5a. the geometry is a simple droplet on a surface that results in around 30,000 DOF (quadratic elements). After initilization, the model solves ok up until higher times (~350, in steps of 0.1)where it gives me an <out of memory error> or <failed to find initial conditions>.

When looking at the task manager while the solution takes place it seems that COMSOL's memory consumption increases with time stepping until it reaches a max value (say 1.4GB in my computer) before failing. This memory does not get released by the program and restarting comsol becomes neccessary.

Has any one encountered this problem before? the program seems to work fine if other modulues are used (such as fluid flow).

Kind regards,
Laith
5 Replies Last Post Apr 22, 2010, 2:42 p.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Apr 21, 2010, 1:57 a.m. EDT
Hi

As a general rule for myself, on MS windos and UX, one done major solve, I always restart comsol as memory gets fragmented and the OS + programme does not manage to compress it without a restart, luckily 3.5 start quickly
Have fun Comsoling
Ivar
Hi As a general rule for myself, on MS windos and UX, one done major solve, I always restart comsol as memory gets fragmented and the OS + programme does not manage to compress it without a restart, luckily 3.5 start quickly Have fun Comsoling Ivar
Laith Hurmez
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Posted: 1 decade ago Apr 21, 2010, 3:51 p.m. EDT
Thanks for the comments Ivar. is there any reason why the memory quickly climbs up in my case? I tried solving other problems using the predefined models (such as the static mixer problem) and I don't get memory issues. when looking at the task manager the memory usually increases and decreases as the solution takes place, my memory only increases!

in terms of the solution it does converge pretty quickly so I'm having difficulties pinning down the cause of the issue.

Thanks again for the help!

Laith
Thanks for the comments Ivar. is there any reason why the memory quickly climbs up in my case? I tried solving other problems using the predefined models (such as the static mixer problem) and I don't get memory issues. when looking at the task manager the memory usually increases and decreases as the solution takes place, my memory only increases! in terms of the solution it does converge pretty quickly so I'm having difficulties pinning down the cause of the issue. Thanks again for the help! Laith
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Apr 21, 2010, 4:32 p.m. EDT
Hi

sometimes the plot while solving or the probe plots might help to identify what is going wrong, there is also the log file that sometimes gives you a clue

I do not have many other comments for your case, unfortunately

Goog luck
Ivar
Hi sometimes the plot while solving or the probe plots might help to identify what is going wrong, there is also the log file that sometimes gives you a clue I do not have many other comments for your case, unfortunately Goog luck Ivar
R. F. Hamou
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Posted: 1 decade ago Apr 22, 2010, 1:10 p.m. EDT
Hi,

To minimize such effect you can use the option in : solver parameter -> advanced ->store solution on file.

I hope it helps

Cheers
Hi, To minimize such effect you can use the option in : solver parameter -> advanced ->store solution on file. I hope it helps Cheers
Laith Hurmez
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Posted: 1 decade ago Apr 22, 2010, 2:42 p.m. EDT
Hi Faycal,

Yea I managed to find this in the help files yesterday, it certainly solved the issue. Thanks very much!

Laith
Hi Faycal, Yea I managed to find this in the help files yesterday, it certainly solved the issue. Thanks very much! Laith

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