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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 The information provided may be out of date.

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The second argument of the d() operator must be a variable name.

Posted 2011年8月25日 GMT-4 11:01 Studies & Solvers Version 4.2, Version 4.2a 7 Replies

Leanne Nixon
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For two of the models that I'm trying to run I keep getting the following error:

"The second argument of the d() operator must be a variable name."

I do not understand what that means, and I cannot find anywhere how to try and fix the problem.

Any suggestions?

Thanks!
7 Replies Last Post 2012年1月11日 GMT-5 05:18
COMSOL Moderator

Hello Leanne Nixon

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If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.

Marjan
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Posted: 1 decade ago 2011年12月6日 GMT-5 09:37
Hi,
I also have the same problem in 4.2.a version. Any suggestion? I am using structural mechanics module.

Marjan
Hi, I also have the same problem in 4.2.a version. Any suggestion? I am using structural mechanics module. Marjan
Magnus Ringh COMSOL Employee

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Posted: 1 decade ago 2011年12月6日 GMT-5 10:27
Hi,

Make sure that all differentiation operators in the model have valid variable names as their second argument (the variable that you differentiate with respect to). For example,

d(x*y,x)

is valid but

d(x*y,1) or d(x*y,2*x)

give the error that you report.

Best regards,
Magnus Ringh, COMSOL
Hi, Make sure that all differentiation operators in the model have valid variable names as their second argument (the variable that you differentiate with respect to). For example, d(x*y,x) is valid but d(x*y,1) or d(x*y,2*x) give the error that you report. Best regards, Magnus Ringh, COMSOL
Marjan
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Posted: 1 decade ago 2011年12月6日 GMT-5 10:48
Hi again,

Thanks for the reply. I solved it by removing the check mark for nearly in-compressible material. I did not have any analytic function that uses d function.

Yours,
Marjan
Hi again, Thanks for the reply. I solved it by removing the check mark for nearly in-compressible material. I did not have any analytic function that uses d function. Yours, Marjan
Chiwei Ong
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Posted: 1 decade ago 2011年12月9日 GMT-5 05:56
Hi, I am just using 4.2a. and wish to know more about it.

When i formulate the hyperelastic material using Mooney Rivlin material,
the same error pop up.

May I know why Mooney Rivlin material will be involve into problem?
as i use Neo hookean material, all the things done smoothly.
Hi, I am just using 4.2a. and wish to know more about it. When i formulate the hyperelastic material using Mooney Rivlin material, the same error pop up. May I know why Mooney Rivlin material will be involve into problem? as i use Neo hookean material, all the things done smoothly.
Lars Gregersen COMSOL Employee

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Posted: 1 decade ago 2011年12月9日 GMT-5 06:41
Hi

You should try the update for Comsol 4.2a:
www.comsol.com/support/updates

It solves a specific problem with the structural mechanics module that causes this problem.

--
Lars Gregersen
Comsol Denmark
Hi You should try the update for Comsol 4.2a: http://www.comsol.com/support/updates It solves a specific problem with the structural mechanics module that causes this problem. -- Lars Gregersen Comsol Denmark
Chiwei Ong
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Posted: 1 decade ago 2011年12月9日 GMT-5 07:00
Dear Lars Gregersen ,

Thank you.
I will try it on monday,as now do not have comsol in my computer.

will update you all information whether i solve it or not.
Dear Lars Gregersen , Thank you. I will try it on monday,as now do not have comsol in my computer. will update you all information whether i solve it or not.
Peter Varga
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Posted: 1 decade ago 2012年1月11日 GMT-5 05:18
Dear All,

I can confirm that this problem is removed by the Update 2.

Best,
Peter
Dear All, I can confirm that this problem is removed by the Update 2. Best, Peter

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