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error: Failed to evaluate expression

Posted Jan 23, 2011, 2:37 p.m. EST Low-Frequency Electromagnetics 7 Replies

Pengxin Zhang
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Hello,

I want to simulate water flowing in the soil when raining.I used Laminar Flow (spf). In the material properties, i choose:
Permeability: 0.43 m^2
Porosity: 0.3
Density 1860 kg/m^3

But after running, I got the following information:
"The following feature has encountered a problem:
-- feature: stationary solver 1 (sol1/s1)
-- error: Failed to evaluate expression"

Can anybody tell me what's wrong with the program?

thanks
Pengxin

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7 Replies Last Post Jun 8, 2013, 1:51 p.m. EDT
mb
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Posted: 1 decade ago Jan 24, 2011, 3:36 a.m. EST
Hi,

you must connect your material definition to your domain under the material tab.

Best wishes, Marcel
Hi, you must connect your material definition to your domain under the material tab. Best wishes, Marcel
Pengxin Zhang
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Posted: 1 decade ago Jan 24, 2011, 4:03 a.m. EST
Hello Marcel,

Thank you very much!

I defined the material again. but as previously, the " Dynamic viscosity" automatic come out. Because the transfer media is soil, I am wondering if it is neccessary to define it, and how to define. But if i do not define it, it appears the same error as before.

best regards,

Pengxin
Hello Marcel, Thank you very much! I defined the material again. but as previously, the " Dynamic viscosity" automatic come out. Because the transfer media is soil, I am wondering if it is neccessary to define it, and how to define. But if i do not define it, it appears the same error as before. best regards, Pengxin
mb
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Posted: 1 decade ago Jan 24, 2011, 4:27 a.m. EST
For me it seems you didn't choose the appropriate application mode.

In laminar flow mode you have at least to define mass density and viscosity. Your definitions of permeability and porosity are not used by laminar flow mode. (Note the symbols under Material 1 after trying to solve the model)

I think you should try any of the chemical species transport modes (chpm).
For me it seems you didn't choose the appropriate application mode. In laminar flow mode you have at least to define mass density and viscosity. Your definitions of permeability and porosity are not used by laminar flow mode. (Note the symbols under Material 1 after trying to solve the model) I think you should try any of the chemical species transport modes (chpm).
Pengxin Zhang
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Posted: 1 decade ago Jan 24, 2011, 6:25 a.m. EST
I tried the chemical species transport modes, but I just want to get the volecity of water (the volecity of rain in soil). i have no data of species contrentration. I think COMSOM3.5 can handle it. 4.0 can not? or do you know any other program to solve it?
I tried the chemical species transport modes, but I just want to get the volecity of water (the volecity of rain in soil). i have no data of species contrentration. I think COMSOM3.5 can handle it. 4.0 can not? or do you know any other program to solve it?
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Jan 24, 2011, 8:34 a.m. EST
Hi

if 3.5 can, v4 should do, in any case, better :)
but your domain is not my speciality so I'm not the best to give you useful advices

--
Good luck
Ivar
Hi if 3.5 can, v4 should do, in any case, better :) but your domain is not my speciality so I'm not the best to give you useful advices -- Good luck Ivar
Pengxin Zhang
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Posted: 1 decade ago Jan 26, 2011, 3:44 a.m. EST
thanks!
I know the reason why i am fail now, because i did not get the complete version before. Richards' equation can solve my problem now. but another problem comes, after calculating, I want the results is shown by different ways, for example, pressure & depth; velocity & depth, etc. I know it can, but do not know how to realise it.

can you give me a favour!

regards,
Pengxin
thanks! I know the reason why i am fail now, because i did not get the complete version before. Richards' equation can solve my problem now. but another problem comes, after calculating, I want the results is shown by different ways, for example, pressure & depth; velocity & depth, etc. I know it can, but do not know how to realise it. can you give me a favour! regards, Pengxin

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Jaskaran Singh
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Posted: 1 decade ago Jun 8, 2013, 1:51 p.m. EDT
I am using 2-D axial symmetry, quasi-static magnetic- azimuthal - Transient analysis.
for Pulsed eddy current probe.

I want to get the integrated magnetic vector potential on some subdomain.
I have used this command :

IL(k,:)=postint(fem,'2*pi*r*(Aphi_emqa)','unit','Wb*m^2','dl',[4],'edim',2,'intorder',4,'geomnum',1,'solnum',k,'phase',0);

But I am getting error.:
Error: Failed to evaluate expression.
Expression: 2*pi*r*Aphi_emqa
Error: Failed to evaluate variable.
Variable: Aphi_emqa
Geometry: 1
Subdomain: 4
Error: Evaluation of post processing expression failed

How should I remove this error?
I am using 2-D axial symmetry, quasi-static magnetic- azimuthal - Transient analysis. for Pulsed eddy current probe. I want to get the integrated magnetic vector potential on some subdomain. I have used this command : IL(k,:)=postint(fem,'2*pi*r*(Aphi_emqa)','unit','Wb*m^2','dl',[4],'edim',2,'intorder',4,'geomnum',1,'solnum',k,'phase',0); But I am getting error.: Error: Failed to evaluate expression. Expression: 2*pi*r*Aphi_emqa Error: Failed to evaluate variable. Variable: Aphi_emqa Geometry: 1 Subdomain: 4 Error: Evaluation of post processing expression failed How should I remove this error?

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