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Error with Air as a medium material in calculating electrostatic force

Posted Jul 7, 2011, 2:50 a.m. EDT Studies & Solvers Version 4.0a 8 Replies

Mohamed Aref
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Hello all,

I want to calculate the electrostatic force due to parallel plate capacitor, and the medium is air, so i make to plates and make a large Box and set its material >> Air

Now i use three physics: Electrostatic - Solid Mechanics - Moving Mesh.

But i usually have this error, and i want help in solving it.

- - - - - - - - - - - - - - - - - - - - - - - - -
Segregated group X1
Failed to evaluate variable.
- Variable: mat.epsilonr22
- Geometry: 1
- Domain: 6
Failed to evaluate variable.
- Variable: mod1.es.epsilonryy
- Defined as: mat.epsilonr22
Failed to evaluate variable.
- Variable: mod1.es.Dy
- Defined as: (mod1.es.Ey*(epsilon0_const*mod1.es.epsilonryy))
Failed to evaluate expression.
- Expression: d((-mod1.es.Dx*test(mod1.Vx)-mod1.es.Dy*test(mod1.Vy)-mod1.es.Dz*test(mod1.Vz))*(dvol_spatial),{test@1})
- - - - - - - - - - - - - - - - - - - - - - - - -

the model is attached, Thanks.
8 Replies Last Post Nov 23, 2011, 1:41 p.m. EST
Yoann Many
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Posted: 1 decade ago Jul 7, 2011, 3:31 a.m. EDT
there is no model....
there is no model....
Mohamed Aref
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Posted: 1 decade ago Jul 7, 2011, 4:55 a.m. EDT

there is no model....


Sorry
[QUOTE] there is no model.... [/QUOTE] Sorry

Attachments:

Dennis Brown
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Posted: 1 decade ago Jul 7, 2011, 9:53 a.m. EDT


there is no model....


Sorry


The first error you are getting is

"Segregated group X1
Failed to evaluate variable.
- Variable: mat.epsilonr22
- Geometry: 1
- Domain: 6"

I looked at your materials and domain 6 has no selection. I am not sure what you are doing with your simulation but what you need to do is add a material to domain 6. What I did was to add it to the poly-si material and that error went away. In re-running the simulation again, I got this error as a new one:

"Segregated group 2
Failed to evaluate variable.
- Variable: mod1.es.nTz_Fes
- Geometry: 1
- Boundary: 20
Failed to evaluate expression.
- Expression: d((mod1.es.nTx_Fes*test(mod1.u)+mod1.es.nTy_Fes*test(mod1.v)+mod1.es.nTz_Fes*test(mod1.w))*(dvol),{test@2})"

This would seem to imply a boundary condition is not set right in your model. Not sure how to correct it since I am not all that familiar with your model.

Sometimes errors are real easy to spot just because I have done them on my own. When I see a "mat.epsilon" based error, I know that some domain/BC does not have a material assigned or has an empty value associated with it. BC errors can be a bit more difficult to solve as getting the physics right can be tricky.



[QUOTE] [QUOTE] there is no model.... [/QUOTE] Sorry [/QUOTE] The first error you are getting is "Segregated group X1 Failed to evaluate variable. - Variable: mat.epsilonr22 - Geometry: 1 - Domain: 6" I looked at your materials and domain 6 has no selection. I am not sure what you are doing with your simulation but what you need to do is add a material to domain 6. What I did was to add it to the poly-si material and that error went away. In re-running the simulation again, I got this error as a new one: "Segregated group 2 Failed to evaluate variable. - Variable: mod1.es.nTz_Fes - Geometry: 1 - Boundary: 20 Failed to evaluate expression. - Expression: d((mod1.es.nTx_Fes*test(mod1.u)+mod1.es.nTy_Fes*test(mod1.v)+mod1.es.nTz_Fes*test(mod1.w))*(dvol),{test@2})" This would seem to imply a boundary condition is not set right in your model. Not sure how to correct it since I am not all that familiar with your model. Sometimes errors are real easy to spot just because I have done them on my own. When I see a "mat.epsilon" based error, I know that some domain/BC does not have a material assigned or has an empty value associated with it. BC errors can be a bit more difficult to solve as getting the physics right can be tricky.
Mohamed Aref
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Posted: 1 decade ago Jul 7, 2011, 12:21 p.m. EDT



there is no model....


Sorry


The first error you are getting is

"Segregated group X1
Failed to evaluate variable.
- Variable: mat.epsilonr22
- Geometry: 1
- Domain: 6"

I looked at your materials and domain 6 has no selection. I am not sure what you are doing with your simulation but what you need to do is add a material to domain 6. What I did was to add it to the poly-si material and that error went away. In re-running the simulation again, I got this error as a new one:

"Segregated group 2
Failed to evaluate variable.
- Variable: mod1.es.nTz_Fes
- Geometry: 1
- Boundary: 20
Failed to evaluate expression.
- Expression: d((mod1.es.nTx_Fes*test(mod1.u)+mod1.es.nTy_Fes*test(mod1.v)+mod1.es.nTz_Fes*test(mod1.w))*(dvol),{test@2})"

This would seem to imply a boundary condition is not set right in your model. Not sure how to correct it since I am not all that familiar with your model.

Sometimes errors are real easy to spot just because I have done them on my own. When I see a "mat.epsilon" based error, I know that some domain/BC does not have a material assigned or has an empty value associated with it. BC errors can be a bit more difficult to solve as getting the physics right can be tricky.


Hi, Thank you very much.
I'll try to solve the material error now, and for the Force error i'll try and tell you the result
Again, Thank you very much, Mohamed.
[QUOTE] [QUOTE] [QUOTE] there is no model.... [/QUOTE] Sorry [/QUOTE] The first error you are getting is "Segregated group X1 Failed to evaluate variable. - Variable: mat.epsilonr22 - Geometry: 1 - Domain: 6" I looked at your materials and domain 6 has no selection. I am not sure what you are doing with your simulation but what you need to do is add a material to domain 6. What I did was to add it to the poly-si material and that error went away. In re-running the simulation again, I got this error as a new one: "Segregated group 2 Failed to evaluate variable. - Variable: mod1.es.nTz_Fes - Geometry: 1 - Boundary: 20 Failed to evaluate expression. - Expression: d((mod1.es.nTx_Fes*test(mod1.u)+mod1.es.nTy_Fes*test(mod1.v)+mod1.es.nTz_Fes*test(mod1.w))*(dvol),{test@2})" This would seem to imply a boundary condition is not set right in your model. Not sure how to correct it since I am not all that familiar with your model. Sometimes errors are real easy to spot just because I have done them on my own. When I see a "mat.epsilon" based error, I know that some domain/BC does not have a material assigned or has an empty value associated with it. BC errors can be a bit more difficult to solve as getting the physics right can be tricky. [/QUOTE] Hi, Thank you very much. I'll try to solve the material error now, and for the Force error i'll try and tell you the result Again, Thank you very much, Mohamed.
Mohamed Aref
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Posted: 1 decade ago Jul 7, 2011, 4:03 p.m. EDT
I tried to solve the second error but i can't
- - - - - - - - - - - - - - - - - - - - - - -
Segregated group X2
Failed to evaluate variable.
- Variable: mod1.es.nTx_Fes
- Geometry: 1
- Boundary: 23
Failed to evaluate expression.
- Expression: d((mod1.es.nTx_Fes*test(mod1.u)+mod1.es.nTy_Fes*test(mod1.v)+mod1.es.nTz_Fes*test(mod1.w))*(dvol),{test@1})
- - - - - - - - - - - - - - - - - - - - - - -

so if any one understant this error tell me, Great thanks,
Mohamed.

the model is attached after solving the first error.
I tried to solve the second error but i can't - - - - - - - - - - - - - - - - - - - - - - - Segregated group X2 Failed to evaluate variable. - Variable: mod1.es.nTx_Fes - Geometry: 1 - Boundary: 23 Failed to evaluate expression. - Expression: d((mod1.es.nTx_Fes*test(mod1.u)+mod1.es.nTy_Fes*test(mod1.v)+mod1.es.nTz_Fes*test(mod1.w))*(dvol),{test@1}) - - - - - - - - - - - - - - - - - - - - - - - so if any one understant this error tell me, Great thanks, Mohamed. the model is attached after solving the first error.

Attachments:

Dennis Brown
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Posted: 1 decade ago Jul 7, 2011, 4:33 p.m. EDT

I tried to solve the second error but i can't
- - - - - - - - - - - - - - - - - - - - - - -
Segregated group X2
Failed to evaluate variable.
- Variable: mod1.es.nTx_Fes
- Geometry: 1
- Boundary: 23
Failed to evaluate expression.
- Expression: d((mod1.es.nTx_Fes*test(mod1.u)+mod1.es.nTy_Fes*test(mod1.v)+mod1.es.nTz_Fes*test(mod1.w))*(dvol),{test@1})
- - - - - - - - - - - - - - - - - - - - - - -

so if any one understant this error tell me, Great thanks,
Mohamed.

the model is attached after solving the first error.


I took a more detailed look at this and I think it is yelling at you because it doesn't know what the "es.nTx_Fes" function is. There looks to be nothing in your parameters or variables to tell comsol what it is. Boundary 23 is called out in the "boundary load 1" under solid mechanics and you just have this as a user defined option. While that is fine to do, I just don't see where you told comsol more info about this function. Maybe your syntax is wrong?


[QUOTE] I tried to solve the second error but i can't - - - - - - - - - - - - - - - - - - - - - - - Segregated group X2 Failed to evaluate variable. - Variable: mod1.es.nTx_Fes - Geometry: 1 - Boundary: 23 Failed to evaluate expression. - Expression: d((mod1.es.nTx_Fes*test(mod1.u)+mod1.es.nTy_Fes*test(mod1.v)+mod1.es.nTz_Fes*test(mod1.w))*(dvol),{test@1}) - - - - - - - - - - - - - - - - - - - - - - - so if any one understant this error tell me, Great thanks, Mohamed. the model is attached after solving the first error. [/QUOTE] I took a more detailed look at this and I think it is yelling at you because it doesn't know what the "es.nTx_Fes" function is. There looks to be nothing in your parameters or variables to tell comsol what it is. Boundary 23 is called out in the "boundary load 1" under solid mechanics and you just have this as a user defined option. While that is fine to do, I just don't see where you told comsol more info about this function. Maybe your syntax is wrong?
Mohamed Aref
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Posted: 1 decade ago Jul 7, 2011, 11:36 p.m. EDT
Dennis Brown

Thank you very much, the problem is solved.
Dennis Brown Thank you very much, the problem is solved.
Geoffrey Lee
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Posted: 1 decade ago Nov 23, 2011, 1:41 p.m. EST
I am getting the same final error as you did before you fixed it. Can you give some insight as to how you got past it?
I am getting the same final error as you did before you fixed it. Can you give some insight as to how you got past it?

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