Discussion Forum

Hi

read arefully the documentation on Entities and Objects in V4, it's too lon to write it all here. Mostly you use "union" assembly is for contact and specific user physics, but there are far more behind. Take the time its really worth it to understand what Entities are for, and how they are created from the geoemtry

--
Good luck
Ivar

Hi

read arefully the documentation on Entities and Objects in V4, it's too lon to write it all here. Mostly you use "union" assembly is for contact and specific user physics, but there are far more behind. Take the time its really worth it to understand what Entities are for, and how they are created from the geoemtry

--
Good luck
Ivar

Thanks Ivar, I'm sorry I cannot find the documentation on Entities and Objects. Which documentation?

Hi

Start with, get the 4.1 doc, i.e p177 user guide

there are more in the others docs too (use an indexer on your COMSOL pdf doc to quickly search inside them)

--
Good luck
Ivar

Hi Ivar,

Thanks for your information.
I have the same question but I couldnt find the document you mentioned, would you please put the link where this document is located?

Regards
Yashar

Hello Yashar,

you can find a very detailed explanation just typing "The Finalize Node—Finalizing the Geometry" in the Comsol Documentation: once you have opened Comsol, click on the icon with the interrogative point. Or you can equally go to Help > Documentation. Or you can just click Ctrl+F1. I think that explanation is identical to that mentioned by Ivar!

Kind regards

How can I use union and assembly in the same model?.

I mean, can I define union for two bodies and assembly for a third one?

Than you!
Ivan Renteria

Yes. You can first form a union of the two parts. then, when you finalize your geometry, you click "form an assembly" which will assemble the remaining parts. The union can specify to keep the internal boundaries which has the same affect as a "form a union". A mesh of the union parts will match on the boundaries, whereas, the mesh of the assembly parts can have un-matched mesh if you desire and specify that way,

Hi Ivar

I have a question about combine both Solid Mechanics and Inductive heating together. What finalization method should I use?

I've built an inductive heating model with 3d and frequency-transient followed by the tutorial video. It works well when i applied the finalization method to Form a union. But when I changed it to Form a assembly, after the computation finished, there are no error reported and there are no results neither. I mean no results at all.

I've tried several times, the only thing i changed is finalization method, with Form a union there are nice results and with Form assembly there are no results.

The reason I want to use the Form assembly is I want to simulate the mechanical contact at same time. I want to simulate the mechanical contact first, and then simulate the inductive heating effects for different contact pressures. The initial values of variables solved for inductive heating is set as the last value of the mechanical contact solution.

I can get good results for independent physics applied either for mechanical contact or inductive heating. But when I tried to combined them together, there are errors.

Would you please give me some suggestions about it?

Best regards

Hi

When you apply "assembly" mode then all geometrical bodies not grouped by explicit or implicit "unions" will keep their Boundaries, also when in contact. You will not see any difference visually, but if you check the ID lists you will have far more boundaries in Assembly mode than in Union mode, as all common boundaries are double the "up and "don" ones. Furthermore COMSOL will not apply continuity conditions for flux across these boundaries, that you must do manually yourself, which can be quite tedious.

Therefore you should use add in the geometry unions for all items where continuity should apply by default, and keep the assembly only for the boundaries you want to de-double. Then you should use the make imprints check box and then manually control, for each physics, that your flux continuation is correctly set up by defining corresponding "pairs" between all adjacent boundaries

That's the theory, still in practice, often one can get around without the assembly mode, if you have a combination of Solid and ACDC normally you do not need assembly mode for contacts of solids surrounded by air as the air should not be comprised in the SOLID physics. However with contact physics of an air domain that you use in another physics you have an issue: you change the topology that is in the contact region you create new boundaries and new domains, this cannot be handled automatically. My workaround there is to use a small gap of air so that the contact is closed but still allows for the air material domain to exist and not separate. But this requires often automatic remising and some tweaking of the solver settings. Another way is to separate completely, and restart for the new physics once the contact is closed, but this I believe does not apply to your case, as I read you

--
Good luck
Ivar

Hello All,
Regarding Form Union and Form Assembly, you will find this article helpful:
www.comsol.com/support/knowledgebase/1216/