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Distributed Heat Source and model coupling

Posted Feb 3, 2012, 2:27 p.m. EST Heat Transfer & Phase Change, Parameters, Variables, & Functions Version 3.5a, Version 4.2 3 Replies

Alexander Malzkuhn
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Hello everybody,

I have to convert a model for a simulation of SLM-process from Comsol 3.5a to version 4.2. The whole simulation consists of two models. One model for the material, which will be molten and one modell for the heat source, which calculates the intensity distribution of the laser. The dependet variable for the intensity is I. The 3.5a version model uses a extrusion variable from the powder domain to the laser heat source model domain, which is named T. In the material domain, T is the temperature of the model. The intensity I and the temperature in the material model are linked via a weak form PDE in the heat source model, but this did not work for me in the version 4.2.

So I tried to couple both models the other way round. The transmitted heat in W/m³ is a function of the intensity I. I defined a general extrusion operator named 'laser_extru' from the heat source model to the powder domain. I added a heat source node to the heat transfer module. For Q in W/m³ I added my function 'some_coefficents*mod2.laser_extru(Intens)' with Intens=mod2.I. When I try to solve the problem, I get an error, that the interpolation of the extrusion operator did not work, because no origin could be found and the operator Jacobian could not be computed. I am new to Comsol so I'm not familiar with the extrusion operator concept. Does anybody have a hint for me?

I also had a look at this model (www.comsol.com/showroom/gallery/699/). They used almost exactly the same weak PDE as it is used in the version 3.5a model, but my port to the version 4.2 just does not work.
3 Replies Last Post Mar 22, 2012, 7:27 a.m. EDT
Alexander Malzkuhn
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Posted: 1 decade ago Feb 6, 2012, 8:34 a.m. EST
I studied the modell from the database a bit mor in detail. They do almost the same as I want to do. They use a distributed heat source, defined by a weak form PDE and coupled to the temperature in another model by a formula of the type

(Ix-linear_coefficient*I)*test(I)+some_coefficents*I*test(T) with I as dependent variable of model 2, T defined as T = mod1.genext1.extracpl_souce_T and in model 1 the variable extracpl_source_T = T, the temperature of model 1. I use the same formula type, but I have a 3D heat source instead of 1D. In my modell it just doesn't work. Could it be something in the solver settings?
I studied the modell from the database a bit mor in detail. They do almost the same as I want to do. They use a distributed heat source, defined by a weak form PDE and coupled to the temperature in another model by a formula of the type (Ix-linear_coefficient*I)*test(I)+some_coefficents*I*test(T) with I as dependent variable of model 2, T defined as T = mod1.genext1.extracpl_souce_T and in model 1 the variable extracpl_source_T = T, the temperature of model 1. I use the same formula type, but I have a 3D heat source instead of 1D. In my modell it just doesn't work. Could it be something in the solver settings?
Alexander Malzkuhn
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Posted: 1 decade ago Feb 8, 2012, 7:20 a.m. EST
Ok, I did not really solve the problem but did some kind of workaround. Instead of two models I now use just one model. I added the weak PDE physics to my material domain model and added the same PDE but without the extrusion coupling operator und now it works like a charm. I had to do some tricks for the movement but it least this part works.
Ok, I did not really solve the problem but did some kind of workaround. Instead of two models I now use just one model. I added the weak PDE physics to my material domain model and added the same PDE but without the extrusion coupling operator und now it works like a charm. I had to do some tricks for the movement but it least this part works.
Marcus Kerth
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Posted: 1 decade ago Mar 22, 2012, 7:27 a.m. EDT
Hey,

I got the same problem as you do.

Did you transferred everything (PDE,...) to one model without coupling?
How have you solved the problem of motion?

I'm trying to solve something similar.


Thanks.
Hey, I got the same problem as you do. Did you transferred everything (PDE,...) to one model without coupling? How have you solved the problem of motion? I'm trying to solve something similar. Thanks.

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