Discussion Forum

Hi

indeed after having applied different operations I find it too rather tought to edit a geometric model inside COMSOL, I use generally 2 approaches:

1) as you said, if you have not reset your model, I look at the last section of the "history file and edit the file, and rename it myfile.m then I reload it (this does not always work as its easy to edit too much and then COMSOL cannot find it's way through the file structure, then you have still the matlab linked to comsol approach, and you reload your "fem" structure into COMSOL.

2) I select my composed object and I use the geometrical properties, if your grid is fine enough (see how to change in the doc) you can draw the end points with the mouse, but you must reconstruct the closed polyline.
Then you convert to a solid.
Other way: I dissociate my object (convert to lines and then split) and then I work on the lines, before I reselect all and convert back to a solid. You can also change the dimensions in the numerical side of the geoemtry property window.

I advise you to start to play with object decomposition on a fresh file with a simple object, so you learn how use the fonctions

If you are in 3D, its more tricky, you could try method 2, sometimes it works, the recomposition is slightly more tough, it doesn always work for me.

Finally, I use a CAD tool for complex geometries, it's much easier, but generally I have the CAD model ready for construction too.

In the new version V4 rebuilding a geometry will be easier we saw at the conference this automn, I hope this will help for the futur

In the mean time, good luck
Ivar

hi sir,
we have worked on a mems model using COMSOL 3.5a. It was user friendly. now we started working on version 4.1. Here option are difficult to find. i have a problem with updating geometry. can you please help me out.

Hi

I agree in the beginning one is lost, when junping from 3.5 to 4 like that. I was lucky and went to the COMSOL Conference (for me it was in 2009 here in EU, also last ear in Paris) There in 1 hour presentation the COMSOL perons gaveus a good tutorail, after that I found it really nice and better than 3.5. But Ihad this opportunity. Now several, and improved, presentations have been loaded up as tutorials and videos on the main COSMOL site. On really need to start from scratch, take a day or two following the explanations of the detailed models described.

Then only start to build our own models. It will go much quicker for you like that. I have left as much as possible of my findings along the track on the several threads I have replied to here on the forum. Try a search. Such "revolutions" of the software interface are painful for the users, and I mostlyx very critical to them. This time I was very positively impressed, once I understood the principle proposed by COMSOL. Since then I hate to go back to a 3.5 model !

The geoemtry is rather the same and closer to a standard CAD system now. With several enhansments. The "Finish node" is eally the "geomeanalyze()" command of 3.5a, when you transfor your geometry into entities: domains, boundaries ...

The gerneral rule, always right click on a node as often there are new sub-nodes appearing. And these are subnodes are physics dependent, so sometimes by changing a property or a major setting above then new options as sub-nodes might appear lower down in the structure. There are a few, but really very few cases when changing something far down in a tree sub-nodes you change something "higher" up

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Good luck
Ivar