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What is SYSTEM(216)?

toby.t.norris
I recently started using Patran/Nastran 2018. I just noticed that my nastran input files now have the following command at the top: NASTRAN SYSTEM(216)=YES. I do not recall seeing that with previous patran/nastran versions.  Unfortunately, I cannot find this particular system cell documented in the QRG or any other manual. 
 
Please tell me why there is no mention of system cell 216 in the QRG or any other version 2018 manual.   I would like to know what this command is doing and if it is necessary.  I expect all commands to be documented in your manual.  Am I expecting too much?
 
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    In looking for some information to answer your second question, I came across the only reference to System Cell 216 I have seen... it was in the Numerical Methods User Guide, in the Iterative Solver Solutions section:
     
    "The NASTRAN keyword ITER (equivalent to SYSTEM(216)) is used to select the iterative solution by ITER = YES. The default is ITER = NO."
     
    Of course, ITER is a keyword so it is not defined in the QRG... it is defined in the Installation and Operation Guide.
     
    The Numerical Methods User Guide is where you can find some theory and details about most of these options:
     
     
    When it comes to some CASI specifics, the High Performance Computing User Guide can be helpful:
     
     
    CASI is generally recommended for large solid element dominated models... it does have some limitations related to large number of load cases... check out some of the information there.
     
    In any event, using SMETHOD=ELEMENT is turning on the CASI iterative solver specifically, while SMETHOD=MATRIX it turning on the regular iterative solver using all the defaults. If you want to override the defaults for either form of iterative solver, you can use SMETHOD=n where "n" is the ID of the ITER bulk data entry... this entry gives you total control over the various iterative solver options. These are decently described in the QRG.
     
     
     
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  • 0
    In looking for some information to answer your second question, I came across the only reference to System Cell 216 I have seen... it was in the Numerical Methods User Guide, in the Iterative Solver Solutions section:
     
    "The NASTRAN keyword ITER (equivalent to SYSTEM(216)) is used to select the iterative solution by ITER = YES. The default is ITER = NO."
     
    Of course, ITER is a keyword so it is not defined in the QRG... it is defined in the Installation and Operation Guide.
     
    The Numerical Methods User Guide is where you can find some theory and details about most of these options:
     
     
    When it comes to some CASI specifics, the High Performance Computing User Guide can be helpful:
     
     
    CASI is generally recommended for large solid element dominated models... it does have some limitations related to large number of load cases... check out some of the information there.
     
    In any event, using SMETHOD=ELEMENT is turning on the CASI iterative solver specifically, while SMETHOD=MATRIX it turning on the regular iterative solver using all the defaults. If you want to override the defaults for either form of iterative solver, you can use SMETHOD=n where "n" is the ID of the ITER bulk data entry... this entry gives you total control over the various iterative solver options. These are decently described in the QRG.
     
     
     
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