Hello there, i am trying to use the conjugate heat transfer simulation on an 3D printer.
I created a “flow region” inside and outside thanks to Simscale’s CAD mode”.
The build plate is at 200°C, the air inside is at 150°C and the air outside is at 20°C
I am trying to see the temperature on the edge of the 3D printer, the steel’s faces.
I don’t understand what is wrong or how to solve the error that I am witnessing.
Can somebody help me ?
Here is a link to my project : SimScale
Hi there 
This is probably because some faces belong to more than one region (as they are in contact).
Maybe you can create your external flow volume in a way that it is not touching the edge of the 3D printer?
If anyone else has a suggestion, feel free to contribute
Best regards,
Fillia
Hi,
I noticed that you already have some successful simulations in the project, so I believe you were able to spot the problem in the meantime.
In any case, the issue here is with the wall 2 & wall 3 boundary conditions, which have been defined to interfaces:
This is not allowed, since it overconstrains the system. For more notes, please check the first “Important” box in this documentation page: Contacts & Interfaces in Solid Mechanics and CHT | SimScale
Cheers
Thank you for your help, i was able to run the simulation but, i have another problem.
I think that i didn’t choose the right boundaries, you see i calculated that I should have a temperature of at least 149°C (422°K) at the edge of the steel’s faces, but when I look at the results it shows 85°C (358°K) for the hottest part.
I try to turn of the boundaries of 20°C on the outside flow region that is surrounding the printer and adding a natural convection of 150°C to the flow region inside but when I try to launch the simulation I have this error.
I tried to do it with only one face but the end is the same.
What kind of boundaries should I use?
Hi!
I noticed that you are currently running the case as a transient simulation. Is this a requirement for your analysis? Or would you be interested in the equilibrium state of the system?
Furthermore, as the documentation page that I linked states, defining a boundary condition to an interface (i.e. the interface between two volumes) overconstrains the system and causes the error that you are facing.
In short, the only faces that can receive a boundary condition are the boundaries of your geometry (i.e. the 6 external bounding box faces of your flow region). The other faces cannot receive a boundary condition.
I’d suggest that you go through the LED natural convection cooling tutorial, which should provide you good insights with respect to the set up.
Cheers
Thank you for such a great article, it really helped me to fix my printer.
Thank you!
