Discussion Forum

Posted: 1 decade ago 13 lug 2011, 05:32 GMT-4

Hello David, without having seen your model: I think you should define the domain as a "single turn coil domain" and choose the current there. I think the problem with the external current density is, as you said, that the loop is not closed. Do you get any Resistant losses with the ext. current density? I don't think so. With the single turn coil domain you get them and the field. Greetings

Posted: 1 decade ago 13 lug 2011, 06:52 GMT-4

Hi Thanks but the single coil domain is for azimuthal currents and I have an axial current

Posted: 1 decade ago 13 lug 2011, 09:00 GMT-4

Hi David, I don't think you must close an external current inside the model. You should indeed see a magnetic field with a phi component (in axial symmetry) or x and y components in planar symmetry. Cheers Edgar

Posted: 1 decade ago 13 lug 2011, 19:07 GMT-4

[QUOTE] Hi Thanks but the single coil domain is for azimuthal currents and I have an axial current [/QUOTE] Hey, to be sure we don't talk at cross purposes: Are you trying to simulate it in a 2D axis symmetric system or a normal 2D system? I understood it as a normal 2D system. When you say "axial current", do you mean a current flowing into z-direction, or do you mean a tangential (phi-direction) flowing current (for example around the z-axis)? Because I understood it as a flow into z-direction. When you say "external current", do you mean "external current density", or do you couple your model with e.g. the electrical circuit physics? IF you want to let it flow into z-direction in 2D, a "single turn coil domain" works (Az and Resistant Losses are not zero) [not only at azimuthal currents]. As far as I know, the "external current density" doesn't work here (Az and Resistant Losses are zero). IF you want to let it flow around the z-axis, you can define it with only a phi- component in a cylindrical system, or stay in cartesian coordinates and use parametric circle equations. Perhaps I'm just having a wrong image of you model in my mind. Could you maybe attach it? Greetings

Posted: 1 decade ago 14 lug 2011, 08:59 GMT-4

Hi thanks for your interest the system is 2D axisymmetric, the current flows in the z direction, I am trying to see the B field surrounding this current. attached is a file with the simple geometry, I inject external current density but see no B field. thanks David

Attachments:

• axialtest.mph

Posted: 1 decade ago 14 lug 2011, 09:01 GMT-4

Hi thanks for your interest the system is 2D axisymmetric, the current flows in the z direction, I am trying to see the B field surrounding this current. attached is a file with the simple geometry, I inject external current density but see no B field. thanks David

Attachments:

• axialtest.mph

Posted: 1 decade ago 16 lug 2011, 02:45 GMT-4

Dear David, In a 2D-Axisymmetric analysis, z is the height on your screen (up-down), and phi is the vector that goes into your screen. This is the component that you want: set Jphi to some non-zero value. I have two more tips for your model: 1. Create a large rectangle around the block so that the surrounding field can be calculated correctly. Make sure that there is enough space for the field to be reduced to 5-10% of their maximum value, preferably more. 2: Refine your mesh. I hope that helps. Best regards, Ruud

Posted: 1 decade ago 18 lug 2011, 09:52 GMT-4

Ruud, I think he wants a current in z-direction, not phi. This should generate a Bphi field, but it doesn't in the model. Is it possible to set an external current density in z direction? Cheers Edgar

Posted: 1 decade ago 19 lug 2011, 21:21 GMT-4

Can it model a moving magnet with a stationary coil to produce current (Induced)???