# Default internal boundary conditions

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## Default internal boundary conditions

 This post was updated on . In another post (http://forum.featool.com/Multi-boundary-selection-tp886p887.html) Precise Simulation wrote However, the "Continuity" condition should be the default boundary condition for internal boundaries and should not need to be selected manually. This does not seem to always be the case. I have encountered DC Conductive Media problems where the default internal boundaries is a mixed bag. For example: default_boundary_conditions.feaWhere the default boundary conditions for the internal boundaries (1-108) are mostly "Continuity" but about 25 of them are "Flux discontinuity": >> fea.phys.dc.bdr.sel ans = Columns 1 through 12 -2 -2 -2 -1 -2 -2 -2 -1 -1 -2 -2 -1 Columns 13 through 24 -1 -1 -1 -2 -1 -2 -1 -2 -2 -2 -2 -1 Columns 25 through 36 -1 -1 -2 -2 -1 -2 -2 -2 -2 -1 -1 -2 Columns 37 through 48 -2 -2 -2 -2 -2 -2 -2 -1 -1 -1 -1 -1 Columns 49 through 60 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 Columns 61 through 72 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 Columns 73 through 84 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 Columns 85 through 96 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 Columns 97 through 108 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 Columns 109 through 114 (external boundaries) 2 2 2 2 2 2 1.  Can this be corrected so that all internal boundaries are set to "Continuity"? Or... 2.  If the fea is exported to MATLAB where fea.phys.dc.bdr.sel can be set as desired (1-108 set to "-1" in this case), how could it be imported back to featool for continued processing?  Or is this another of my bad ideas :-) ? Kind regards, Randal
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## Re: Default internal boundary conditions

 Administrator It might be a bug but I would need a clear test case to reproduce the issue. The simple test cases I've tried seem to work as expected, but your model contains so many components and history so it is not really possible to say where something could have gone wrong.
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## Re: Default internal boundary conditions

 Precise Simulation wrote It might be a bug but I would need a clear test case to reproduce the issue. Fair enough.  Everything I tried had at least one (or one additional in the case of 2a & 2b) "Flux discontinuity". I only tried multiple (though nonsensical) objects inside a block. Case1 and Case 2 are independent (start from new model). Case2a and Case2b are continuations of Case2 (Case2a began with Case2 and Case2b began with Case2a.  I only dumped fea.phys.dc.bdr.sel for Case1 and Case2b. case1.feacase1.fescase1.mcase1 >> fea.phys.dc.bdr.sel ans = Columns 1 through 12 -2 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 Columns 13 through 22 -1 -1 -1 -1 2 2 1 2 1 2 Case2 case2.feacase2.fescase2.mCase2a case2a.feacase2a.fescase2a.mCase2b case2b.feacase2b.fescase2b.m>> fea.phys.dc.bdr.sel ans = Columns 1 through 12 -2 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 1 Columns 13 through 24 2 2 2 2 1 -1 -1 -2 -2 -2 -2 -1 Columns 25 through 36 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 Columns 37 through 38 -1 -1 Thanks for taking a look at it. Kind regards, Randal
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## Re: Default internal boundary conditions

 Administrator Thank you for the test cases. I will try to fix it when I get a chance, this will however only be able to affect new models, models with existing defined boundary conditions will not be affected. In this case you can still change them manually as you have been doing, optionally apply the multi-select workaround I described in your previous post on this issue, or load a .fea model file into the Matlab workspace, modify/change, and save it back before loading it into the FEATool GUI, for example:  load path_to_my_model.fea -mat % ... make valid changes to the fea struct save path_to_my_changed_model.fea fea -v7