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Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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error in material builder.

Posted 2012年1月7日 GMT-5 12:56 Low-Frequency Electromagnetics, Fluid & Heat, Materials Version 4.2a 6 Replies

Marian Polak
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Hi.
I have this error in the program

Failed to evaluate variable.
- Variable: mod1.icp.rho

I tried to fix the parameter rho in the material browser, but to no avail.
How do I insert a value into the model for rho?

Thank
6 Replies Last Post 2012年1月8日 GMT-5 10:51
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 2012年1月7日 GMT-5 18:32
Hi

as there is no .mat1. tag sequence in your variable name, perhaps it's not in the mterial section, but a "rho" you define in one of the physics nodes, or sub-nodes

--
Good luck
Ivar
Hi as there is no .mat1. tag sequence in your variable name, perhaps it's not in the mterial section, but a "rho" you define in one of the physics nodes, or sub-nodes -- Good luck Ivar
Marian Polak
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Posted: 1 decade ago 2012年1月8日 GMT-5 05:16
The library's material is a defined precisely.
A model definition to variables defined in such a way because when I defined the icp.rho got an error with the variable name duplication.

So I have to define variable mat1.rho?

But how to define the material belongs to the Air?

I have a stationary model study
When we enter the show default solver option I get error can not create an automatic sequence and no solver is formed.

Thank.
The library's material is a defined precisely. A model definition to variables defined in such a way because when I defined the icp.rho got an error with the variable name duplication. So I have to define variable mat1.rho? But how to define the material belongs to the Air? I have a stationary model study When we enter the show default solver option I get error can not create an automatic sequence and no solver is formed. Thank.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 2012年1月8日 GMT-5 05:30
Hi

well I do not fully understand the need for several "rho", but take care when you define variables, not to use names already defined by COMSOL, you get no warning, as COMSOL allows you to redeefine (sometimes) it's internal variables, but when you do it by error the results get strange ;)

Normally the density rho is obtained from the materials data by a series of name conversion and ends up as "physics_tag.rho" this is done internally.

To better understand the variables and their internal use, turn on the equation view and scroll hrough the lists

--
Good luck
Ivar
Hi well I do not fully understand the need for several "rho", but take care when you define variables, not to use names already defined by COMSOL, you get no warning, as COMSOL allows you to redeefine (sometimes) it's internal variables, but when you do it by error the results get strange ;) Normally the density rho is obtained from the materials data by a series of name conversion and ends up as "physics_tag.rho" this is done internally. To better understand the variables and their internal use, turn on the equation view and scroll hrough the lists -- Good luck Ivar
Marian Polak
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Posted: 1 decade ago 2012年1月8日 GMT-5 06:32
I will try to explain the problem again.
I defined a new model.
In this model, there was no variable icp.rho.
I launched Study compute.
I got error messages from the material icp.rho Air is not defined.
But in the material browser everything is fine.
So I tried to define variables in the model Defines icp.rho.
Then I got an error message that the variable is a duplicate.

And I know now how do I remove error
of icp.rho could not be quantified.
For material in the browser everything is fine.

Thank.
I will try to explain the problem again. I defined a new model. In this model, there was no variable icp.rho. I launched Study compute. I got error messages from the material icp.rho Air is not defined. But in the material browser everything is fine. So I tried to define variables in the model Defines icp.rho. Then I got an error message that the variable is a duplicate. And I know now how do I remove error of icp.rho could not be quantified. For material in the browser everything is fine. Thank.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 2012年1月8日 GMT-5 08:28
Hi

well then I believe you should remove your duplicated variable, the one you defined.
Now "air" data often requires a T and pA as the default material property is dependent on Temperature and Pressure. Are you sure these two are defined in your physics ? If not you need to define the missing(ones) i.e. as Parameters

--
Good luck
Ivar
Hi well then I believe you should remove your duplicated variable, the one you defined. Now "air" data often requires a T and pA as the default material property is dependent on Temperature and Pressure. Are you sure these two are defined in your physics ? If not you need to define the missing(ones) i.e. as Parameters -- Good luck Ivar
Marian Polak
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Posted: 1 decade ago 2012年1月8日 GMT-5 10:51
I found rho for this material..
For the pressure and temperature and I put this value in the material browser.
Is this correct?
Duplicate variable is no longer in the model.
Then I fired long ago.

Thank you.
I found rho for this material.. For the pressure and temperature and I put this value in the material browser. Is this correct? Duplicate variable is no longer in the model. Then I fired long ago. Thank you.

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