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How to set a field with constant value and constant direction EVERYWHERE in a model?

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Does anyone know how to set a constant magnetic field for a model? I mean, I need the magnetic field to have the same direction and magnitude everywhere in my model. By the way, how can I set the direction in the space for this magnetic field?

In the sub domain settings there ares spaces for the "r" and "z" components of the field in axis symmetric mode, but if I want to set a constant or a global variable there are no such fields for components or direction.


I need the magnetic field to have a value of 5T and a direction of 45 degrees with respect to the positive semi x-axi, 45 degrees with respect to the positive semi y-axi and 45 degrees with respect to the positive semi z-axi EVERYWHERE in my model.

Thanks to ALL of you!

4 Replies Last Post 08.11.2010, 04:18 GMT-5

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Posted: 1 decade ago 05.11.2010, 10:56 GMT-4
Igor,

I assume you want to have something like a homogeneous external field in your model. One way to achieve that is to define the magnetic field boundary condition accordingly.
Use the magnetic field boundary condition on all the outer bounaries of your model and set the field vector as you wish. You will then see the respective homogeneous field anywhere inside your model.
Of course any magnetic subdomain will locally distort the field. But that's probably what you do a magnetic model for.

Regards
Edgar
Igor, I assume you want to have something like a homogeneous external field in your model. One way to achieve that is to define the magnetic field boundary condition accordingly. Use the magnetic field boundary condition on all the outer bounaries of your model and set the field vector as you wish. You will then see the respective homogeneous field anywhere inside your model. Of course any magnetic subdomain will locally distort the field. But that's probably what you do a magnetic model for. Regards Edgar

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Posted: 1 decade ago 05.11.2010, 22:34 GMT-4
Thank you very much for your answer. I think I did it.
Sorry to bother, but I have one more question about this.

In 2D axisymmetric mode, at ACDC>Quasistatics Magnetic>Azimuthal Induction Current Vector Potential>Transient Analysis>Subdomain Settings, there are two fields in the dialog box. Their name are Vloop and Velocity. Can you tell me what are those Vloop and Velocity for? Can you recommend to me something to read and learn more about them or an example on how to use them?

Thank you again!
Igor
Thank you very much for your answer. I think I did it. Sorry to bother, but I have one more question about this. In 2D axisymmetric mode, at ACDC>Quasistatics Magnetic>Azimuthal Induction Current Vector Potential>Transient Analysis>Subdomain Settings, there are two fields in the dialog box. Their name are Vloop and Velocity. Can you tell me what are those Vloop and Velocity for? Can you recommend to me something to read and learn more about them or an example on how to use them? Thank you again! Igor

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Posted: 1 decade ago 06.11.2010, 00:22 GMT-4
Edgar,

I told you in my other reply that "I think I did it", but I just did it with the no r-component Magnetic Flux Density case, but now I have just realized that it apparently does not work for the case with no z-component Magnetic Flux Density External Field.

It apparently works if I set the Boundary Condition with only z-component (the magnetic flux density vectors should be ALL pointing upward or downward depending on the sign) and the value is the same everywhere inside the domain (two rectangles of air, one for analysis, one for surroundings, just to practice). The boundary condition at the left side of both rectangles is set to Axisymmetry.

But it's not working if I set the Boundary condition to have only R component. In this case I think ALL the Magnetic Flux Density vectors should be horizontal and with the same value and it's not the case. They are inclined and with different values everywhere. (As for the case with no r-component, the left side of both rectangles are set with a boundary condition of axial symmetry.) What am I doing wrong?

I am attaching the images I see in both case to explain better my situation.

And about my question in relation with the V loop and Velocity fields in the subdomain dialog box, please, any help is well appreciated!

Thank you very much. A thousands thanks!!!
Edgar, I told you in my other reply that "I think I did it", but I just did it with the no r-component Magnetic Flux Density case, but now I have just realized that it apparently does not work for the case with no z-component Magnetic Flux Density External Field. It apparently works if I set the Boundary Condition with only z-component (the magnetic flux density vectors should be ALL pointing upward or downward depending on the sign) and the value is the same everywhere inside the domain (two rectangles of air, one for analysis, one for surroundings, just to practice). The boundary condition at the left side of both rectangles is set to Axisymmetry. But it's not working if I set the Boundary condition to have only R component. In this case I think ALL the Magnetic Flux Density vectors should be horizontal and with the same value and it's not the case. They are inclined and with different values everywhere. (As for the case with no r-component, the left side of both rectangles are set with a boundary condition of axial symmetry.) What am I doing wrong? I am attaching the images I see in both case to explain better my situation. And about my question in relation with the V loop and Velocity fields in the subdomain dialog box, please, any help is well appreciated! Thank you very much. A thousands thanks!!!


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Posted: 1 decade ago 08.11.2010, 04:18 GMT-5
Igor,

the Vloop is a potential diffference around your loop in the angular direction, it creates a loop current according to the resistivity of the subdomain. About the Velocity I am not sure, never used it, try the help function.

Regarding the other question: It is physically not possible to create a homogenous field with a non-zero r-component in an axisymmetric situation. The r-component must be zero on the symmetry axis, otherwise you create a discontinuity at r=0.

Best regards
Edgar
Igor, the Vloop is a potential diffference around your loop in the angular direction, it creates a loop current according to the resistivity of the subdomain. About the Velocity I am not sure, never used it, try the help function. Regarding the other question: It is physically not possible to create a homogenous field with a non-zero r-component in an axisymmetric situation. The r-component must be zero on the symmetry axis, otherwise you create a discontinuity at r=0. Best regards Edgar

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