Processing Error

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guyEANZ
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Processing Error

Post by guyEANZ » Sun Nov 02, 2014 9:21 am -1100

I'm struggling to get usable results out of a foundation detail.
The construction is a SIP panel on a concrete waffle slab (on ground) with a floating floor over.
The calculation runs for about 5 seconds at a normal speed and then suddenly speeds up and completes 99% in a further second or two.
The results, unsurprisingly just show a straight line in all graphs.
I've tried deleting the moisture sources, air cavity and membranes to see if this is the problem, but the calculation still doesn't return anything useful.

Am I missing something obvious?
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Footing 2D.zip
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Christian Bludau
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Re: Processing Error

Post by Christian Bludau » Sun Nov 02, 2014 9:06 pm -1100

Dear Guy,
thats convergence problems you have.

The main problem in your construction is the numerical grid. Your grid is much too coarse. You have to use a steady-going grid as this shows better convergence behavior, than a size-jumping-grid. Please check the expansion factor. It should not be higher than two respectively lower than 0.5.
grid2d.png
Grid left is much too coarse, can cause convergence problems. Right is a nice, steady-going grid.
grid2d.png (84.28 KiB) Viewed 3381 times
Further your rain water sources can cause problems, if a material gets supersaturated during the rain event.

More information on such convergence problems you can find in the following topics:
http://www.wufi-forum.com/viewtopic.php?t=332
http://www.wufi-forum.com/viewtopic.php?t=494
http://www.wufi-forum.com/viewtopic.php?t=789

Best regards,
Christian

StrawConstruction
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Re: Processing Error

Post by StrawConstruction » Sun May 12, 2019 10:27 pm -1100

Hello Christian,
I am also having problems with the grid: is there a way to understand clearly which grid is giving me the lower error? I am working on a simple wall, trying out a 75x75; 100x100; 112x112;130x130;150x150 grid. I would like to confront them to chose the proper oneto use a basis for my following calculations. However I cannot chose a value to confront all of them (I expect to have smaller error with finer grid of course).
Thank you in advance
G.

Christian Bludau
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Re: Processing Error

Post by Christian Bludau » Sun May 12, 2019 10:33 pm -1100

Hi G.
that question can not be answered universal. That is always depending on the construction and layers. Generally spoken a finer grid should produce more accurate results.
Show us a picture of your construction and the grid you selected.
Christian

StrawConstruction
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Re: Processing Error

Post by StrawConstruction » Sun May 12, 2019 10:43 pm -1100

1.PNG
Geometry
1.PNG (12.66 KiB) Viewed 716 times
Here is the geometry. It's a simple wall with brics and EPS insulation.
Griglia 75x75.PNG
Grid 75x75
Griglia 75x75.PNG (21.7 KiB) Viewed 716 times
I tried with many grids, in order to define the most optimized one in terms of time of calculation and error. However I cannot chose the right value to confront all of them and justify my choice.
I attache here all the grids i tried out.
Thank you again
G.
Attachments
1.PNG
1.PNG (12.66 KiB) Viewed 716 times

StrawConstruction
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Re: Processing Error

Post by StrawConstruction » Sun May 12, 2019 10:46 pm -1100

It didn't work with all the pictures. Sorry.
Griglia 100x100.PNG
Grid 100x100
Griglia 100x100.PNG (22.18 KiB) Viewed 716 times
Griglia 112x112.PNG
Grid 112x112
Griglia 112x112.PNG (19.15 KiB) Viewed 716 times
Griglia 130x130.PNG
Grid 130x130
Griglia 130x130.PNG (21.7 KiB) Viewed 716 times

Christian Bludau
WUFI SupportTeam IBP
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Re: Processing Error

Post by Christian Bludau » Sun May 12, 2019 11:08 pm -1100

First one (75x75) looks sufficient for me.
BTW: I would not optimizing the time of calculation. Let the computer do the work during night.
Christian

StrawConstruction
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Re: Processing Error

Post by StrawConstruction » Sun May 12, 2019 11:13 pm -1100

I also think 75 is sufficient... but as I am using it for my thesis I need to justify my choice somehow with numbers... isn't there a way? I tried first to confront the biggest theta and phi values, but the results were not as expected (getting smalle with the finer grid).
Thank you again for your help.
G.

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