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circular variable dependency detected

Posted 22.05.2011, 20:27 GMT-4 Parameters, Variables, & Functions Version 4.1 1 Reply

Muhammad Assad
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I always get this error when I try to run the simulation.

Circular variable dependency detected.
- Variable: mod1.rhos
- Geometry: 1
- Domain: 1
The equations that I have I have defined are

Qom= (Ca*exp(-Ea[J/mol]/(R_const[J/(mol*K)]*T[K]))*log(p[Pa]/Peq[Pa])*(rhoss-rhos))

rhos= (1/(1-eata))*intop1(Qom*t)+8000

Can anybody tell me how to solve this?

Thanks in advance
1 Reply Last Post 15.12.2011, 14:28 GMT-5
COMSOL Moderator

Hello Muhammad Assad

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Yao Zhang
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Posted: 1 decade ago 15.12.2011, 14:28 GMT-5
I have the same problem.

y=f(x(i-1));

x=f(y(i));

where i is time step number

when two variables are dependent on each other and have to iterate sequentially in each time step to update, it came up with the ''circular variable dependency detected' problem. Even though I used a "time discrete solver", and turn on the "Iterative" node in the solver. It is easy to realize in matlab or other language package, but how to do it in comsol.

Hope anyone can answer that.

Thank you

Yao
I have the same problem. y=f(x(i-1)); x=f(y(i)); where i is time step number when two variables are dependent on each other and have to iterate sequentially in each time step to update, it came up with the ''circular variable dependency detected' problem. Even though I used a "time discrete solver", and turn on the "Iterative" node in the solver. It is easy to realize in matlab or other language package, but how to do it in comsol. Hope anyone can answer that. Thank you Yao

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