Line heat source rotating like the handle of a clock

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Hello fellow comsol users,

I am trying to model a heat line source rotating about the center of a circle. While I have seen a lot on rotating heat sources (mostly ways to model rotating or moving laser sources); i cannot for my life think of a method to make it work for a rotating line source. Maybe I am thinking too complicated here.

Also, the heat line source feature seems to work only on edges that are fixed in the geometry, so that doesn't work either.

If any of you have faced this problem yourselfs or has an idea on how to implement it, I would be grateful for any advice you can share.

Thank you in advance! André

PS: I only have the basic license and the heat transfer module license available. If your solution requires another method, please mention the module name as well. Thanks!


1 Reply Last Post Nov 25, 2025, 10:50 a.m. EST
Edgar J. Kaiser Certified Consultant

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Posted: 1 hour ago Nov 25, 2025, 10:50 a.m. EST

Hi Andre,

you can achieve that with a boolean expression that depends on spacial variables. In the example I first defined a cylindrical coordinate system sys2 and I added a boolean expression involving sys2.phi into the temperature BC. You can modify this expression to make the line depend on time or a parameter in order to make it move. Actually it is not exactly a line but rather a sector. You may find a variant that makes a line of defined thickness if this is needed. You may need a finer mesh to make it look a cleaner line (sector).

Hope it helps, Edgar

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Hi Andre, you can achieve that with a boolean expression that depends on spacial variables. In the example I first defined a cylindrical coordinate system sys2 and I added a boolean expression involving sys2.phi into the temperature BC. You can modify this expression to make the line depend on time or a parameter in order to make it move. Actually it is not exactly a line but rather a sector. You may find a variant that makes a line of defined thickness if this is needed. You may need a finer mesh to make it look a cleaner line (sector). Hope it helps, Edgar

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