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Failed to evaluate variable

Posted Feb 27, 2012, 8:45 p.m. EST Chemical Reaction Engineering, Studies & Solvers Version 4.2a 4 Replies

Joo-Youp Lee

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Hello,

I am trying to solve a simple mass balance model based on the reaction kinetic expressions using the Synchronize feature as attached. I have the following questions.

1) Why do I get the “Failed to evaluate variable” message? C_H2 is a variable name used in mod1 and cH2 is one in mod2. Both are defined in the model.

2) Study 2 is automatically generated when I synchronize. Under the “physics selection” setting, do I need to select both of “re” and “chds” or do I need to just select “chds”? I looked at the deNOx model available in the model gallery, and they disconnected the “re” from the rest of the flow models. Why is that and what is the difference?

3) Also, Chemical Reaction Engineering manual says that we can return to and solve the equations defining the ideal reactor model (the ODE model) in the Reaction Engineering interface by clearing the Synchronization with COMSOL Multiphysics check box. But, I found that it does not work for “Study 1”.

Thanks.

Attachments:

Nonisothermal_HI_reactor_7.mph

4 Replies Last Post Sep 24, 2012, 6:57 a.m. EDT

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago

Hi

and I (v4.2a .1§66 as you) get an error "Tag: null" which could indicate some thing is corrupt in the internals of the model, for these things SUPPORT is the best ;)

--
Good luck
Ivar

Joo-Youp Lee

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Posted: 1 decade ago

Thanks, Ivar. I will.

Nawaz Ahmad

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Posted: 1 decade ago

Dear Ivar,

I face also the synchronization failure in 4.2a. COMSOL experts are requested to resolve synchronization problem on priority for 4.2a.

Regards,

Poornima Narayanan

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Posted: 1 decade ago

Hi,
I'm getting this error repeatedly and couldn't solve further.I request help..
Failed to evaluate variable.
- Variable: mod1.u31x
- Geometry: 1
- Domain: 1
Failed to evaluate variable.
- Variable: mod1.chpm.u
- Defined as: mod1.u31x
Failed to evaluate expression.
- Expression: d(((-mod1.chpm.u*mod1.cx-mod1.chpm.v*mod1.cy-mod1.chpm.w*mod1.cz)*test(mod1.c))*(dvol),{test@4})..

Also,
For Maxwell-stefan diffusion,how can i change the values in diffusivity matrix?

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