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Error while solving Joule heating: mesh-case 0 there are 665 void equations (empty rows in matrix) for the variable mod1.V
Posted 20.12.2012, 12:17 GMT-5 Low-Frequency Electromagnetics, Heat Transfer & Phase Change, Studies & Solvers Version 4.2, Version 4.2a 4 Replies
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I tried to simulate joule heating in a copper cylindrical wire with an cylindrical air-void in it. But I am getting following error:
Failed to find a solution.
Singular matrix.
For mesh-case 0 there are 665 void equations (empty rows in matrix) for the variable mod1.V
at coordinates: (1.2,-0.7,2), (1.18384,-0.573893,2), (1.13639,-0.455939,2), (1.13771,-0.941685,2), (1.18418,-0.824792,2), ...
and similarly for the degrees of freedom (empty columns in matrix)
Returned solution is not converged.
I saw similar posts, but couldn't simulate my model still; the model is attached herewith.
Observation: If I take the difference of these two cylinders and remove the air material (i.e. the final geometry would have just the copper wire with a groove), COMSOL is able to solve it. But, I need to simulate the air void too. In one case, I would also like to have the small cylindrical air-void completely inside the bigger cylinder.
Any help is greatly appreciated.
Thanks,
Kapil
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What do you mean you need to simulate the "air void" as air is no solid, and you have no joule heating in air as you have defined no conduction, it's not bringing you anything.
The easiest is to define your copper only ,and add a Convective cooling boundary on all surfaces, including your notch.
Now if you are saying your air volume is closed and you want the heat flow in there, of the air you need to use the correct fluid heat flow model , to take into account conduction as well as mass transport, that is possible with other physics (Conjugated heat flow, or heat flow in fluids, but it's far heavier to use
--
Good luck
Ivar
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Tip: Make sure that all thermal & electrical conductivities are set to non-zero values. Use some small numbers if the default is zero.
this was very helpful to me thank you very much
any idea why this "void" error happens for values of "0"?