Learning Forum

[OROI]

Hi

I'm trying to simulate definition of the ampere, which states that it is the 1 amp constant current will produce an attractive force of 2 × 10–7 newton per metre of length between two straight, parallel conductors of infinite length and negligible circular cross section placed one metre apart in a vacuum. In my model conductor length is 2 meter long, so then total force should be 400 nN. Can somebody check my model and tell me why i'm not getting correct answer. It must done with transient solution, because if can get this definition of the ampere right, then i probably know what is wrong with my other transient simulations.

[Navya Chode]

I am not sure whether your definition or what you have derived by replacing infinite length with 2 meters is correct or not. I am leaving it to you to verify the correctness of this.
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But, I can provide few suggestions to get correct results from the simulation.
1) If not you can perform a 2D simulation first.
2) For very think conductors carrying current, region needs to be very big. Use a very big region.
3) Increase the mesh size to fine settings under initial mesh settings.

Regards Navya

[OROI]

Hi
In 3D magnetostatic solver i can get 200nN per meter if conductor current is 1A, conducotor distance is 1meter and conductor length is 2m. This means that total force is 400nN and i believe that is correct.


If i try solve problem with transient solver, best results what i have got is about half of magnetostatic results with same current and distances. In 3D transient solver i use that A-phi formulation, if A-phi formulation is off then results are about 10 times larger that magnetostatic. I also use in transient solver mesh import option from that magnetostatic model. Result are not getting any better if i change mesh options in magnetostatic to finer. Also i think region should be enough large if i can get correct answers in magnetostatic solver and i use same size region in transient solver.

Can you or somebody send me example model of that transient simulation so i can compare it to my model?