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Convection Simulation from Joule heating / Current Density

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Old   May 30, 2017, 08:40
Default Convection Simulation from Joule heating / Current Density
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Daniel
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Error i get is:
ERROR #004100018 has occurred in subroutine FINMES. Message: Fatal overflow in linear solver.

I am trying to do a transient simulation on CFX 16.2 of convective heating (Laminar Turbulence) from a copper conductor with an AC current (current density input). Also hope to see the induced currents in the encapsulation. Therefore, Electric and Magnetic Field Models are ON on all domains.
2D simulation (z=0,5mm)

Very simple geometry:
Round conductor (copper) -> ideal air -> encapsulation (copper) -> ideal air (opening)


Mesh is max size 0,75mm, if i put 0,5mm i get an error of not having enough space. (RAM = 16GB)
Attached you find relevant settings like adaptive time step, solver control, CFD-post results.
Initial time step = 6E-10s

I let the simulation run 4 time steps without any current input. The 5th time step there is a current input of 0,5A. It diverges on the 6th COEFFICIENT LOOP ITERATION. All iterations before since 1st time step, it shows OK in all equations.

I've been trying to fix this the last 6 days and I've read most posts that got the same error and still haven't fixed it.

Thanks for your time and attention.
Attached Images
File Type: jpg geometry.JPG (29.2 KB, 22 views)
File Type: jpg solver control.JPG (57.2 KB, 26 views)
File Type: jpg analysis type.JPG (64.3 KB, 23 views)
File Type: jpg divergance.JPG (158.3 KB, 23 views)
File Type: jpg mesh.jpg (193.8 KB, 20 views)

Last edited by megaccount; May 30, 2017 at 08:57. Reason: forgot to say it was transient and CFX 16.2
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Old   May 30, 2017, 09:49
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Maxim
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Hi,
1) have you worked through the FAQ?
https://www.cfd-online.com/Wiki/Ansy...do_about_it.3F

2) Can you start from another, finished result?
3) Monitor your RAM usage while you run the simulation and check if you're running out of RAM. 16GB is really nothing when you do more complex transient simulations...
4) Have you tried Ansys 18.1?
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Old   May 30, 2017, 10:02
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Daniel
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Quote:
Originally Posted by -Maxim- View Post
Hi,
1) have you worked through the FAQ?
https://www.cfd-online.com/Wiki/Ansy...do_about_it.3F

2) Can you start from another, finished result?
3) Monitor your RAM usage while you run the simulation and check if you're running out of RAM. 16GB is really nothing when you do more complex transient simulations...
4) Have you tried Ansys 18.1?
Thanks for your reply Maxim.
1) yes.
2) no.
3) I run double precision 6 core parallel. Its at 60%-66% of usage throughout the simulation.
4) no, and i wont be able to :/
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Old   May 30, 2017, 10:50
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I have a feeling its from the \vec{A}->\vec{A} field formulation used in CFX because vector magnetic potential is used in both the conductive and non-conductive regions. The high difference of electric conductivity from copper to air makes this field formulation unstable....
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#004100018, convection, current density, finmes, joul heating

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