Ivar KJELBERG
COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted:
1 decade ago
14 janv. 2011, 14:54 UTC−5
Hi
THe jacobian is build up of the derivatives of the dependent variables, here phi, so something is not well enough defined to allow COMSOL to elaborate the derivatives of phy. Perhaps some contradiction in a BC, or a step function with two derivatives, of different values for the same (probably starting point).
--
Good luck
Ivar
Hi
THe jacobian is build up of the derivatives of the dependent variables, here phi, so something is not well enough defined to allow COMSOL to elaborate the derivatives of phy. Perhaps some contradiction in a BC, or a step function with two derivatives, of different values for the same (probably starting point).
--
Good luck
Ivar
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Posted:
1 decade ago
3 mai 2012, 11:06 UTC−4
Hello Evar,
I am building a model of "capacitive accelerometer". And i got this error.
Moreover, i am not able to find out the dependent variable mod1.u!
Failed to evaluate variable Jacobian.
- Variable: mod1.u
- Geometry: 1
- Boundary: 1 2 3 4 9 11 112 113 114 164 204 206
Can you please help with this?
Thank you
Hello Evar,
I am building a model of "capacitive accelerometer". And i got this error.
Moreover, i am not able to find out the dependent variable mod1.u!
Failed to evaluate variable Jacobian.
- Variable: mod1.u
- Geometry: 1
- Boundary: 1 2 3 4 9 11 112 113 114 164 204 206
Can you please help with this?
Thank you
Ivar KJELBERG
COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
3 mai 2012, 14:49 UTC−4
Hi
it's simply "u", the variable name.
The Jacobian error, most often comes from an initial value or a BC that is defined such that the derivative of u is undefined, The solver uses the estimated derivatives to choose the next solving step, but if you use bolean equations or values that become undefined in the BC definitions then COMSOL might not manage to estimate any derivatives, and then the solver fails.
--
Good luck
Ivar
Hi
it's simply "u", the variable name.
The Jacobian error, most often comes from an initial value or a BC that is defined such that the derivative of u is undefined, The solver uses the estimated derivatives to choose the next solving step, but if you use bolean equations or values that become undefined in the BC definitions then COMSOL might not manage to estimate any derivatives, and then the solver fails.
--
Good luck
Ivar
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
4 mai 2012, 07:30 UTC−4
HI,
I did try changing the boundary and initial conditions. I have attached the model with this message. Can you please check the error in this and let me know how i should proceed?
Thank you
Malavika
HI,
I did try changing the boundary and initial conditions. I have attached the model with this message. Can you please check the error in this and let me know how i should proceed?
Thank you
Malavika