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Time-dependent boundary condition from data file
Posted 3 juin 2011, 11:42 UTC−4 3 Replies
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Hello,
I wonder if someone could offer some insight on this issue. I am doing a very simple 1D transient thermal conduction/convection analysis. I am trying to define a time dependent boundary condition by defining a function which is interpolated from the data in a text file. I got the following error message:
Error: 6250
Failed to evaluate variable Jacabian
- Variable: Tb
- Geometry: 1
- Dimension: 1
- Domains: {1}
Failed to evaluate operator Jacobian
- Operator: mean
Here Tb is the function I am trying to define by interpolation.
If Tb is set to be a constant, it works fine. And I can Tb to another value at the end of the simulation to start another run -- a manual implementation of time-dependent BC.
I searched the forum and it seems that it might have something to do with the smoothness of the BC. I tried different interpolation method, but the results were the same.
I am currently looking for more detailed documentation on the usage of interpolated BC now. Any input would be appreciated.
Thank you!
PS: I am using Comsol3.3
I wonder if someone could offer some insight on this issue. I am doing a very simple 1D transient thermal conduction/convection analysis. I am trying to define a time dependent boundary condition by defining a function which is interpolated from the data in a text file. I got the following error message:
Error: 6250
Failed to evaluate variable Jacabian
- Variable: Tb
- Geometry: 1
- Dimension: 1
- Domains: {1}
Failed to evaluate operator Jacobian
- Operator: mean
Here Tb is the function I am trying to define by interpolation.
If Tb is set to be a constant, it works fine. And I can Tb to another value at the end of the simulation to start another run -- a manual implementation of time-dependent BC.
I searched the forum and it seems that it might have something to do with the smoothness of the BC. I tried different interpolation method, but the results were the same.
I am currently looking for more detailed documentation on the usage of interpolated BC now. Any input would be appreciated.
Thank you!
PS: I am using Comsol3.3
3 Replies Last Post 6 juin 2011, 17:52 UTC−4
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Posted:
1 decade ago
Just an update on some trouble shooting.
I define a new function Tb = 374 to act as a boundary condition and got the same error message regarding Jacobian. If I define Tb as a constant, it works ok.
It looks like I can set up a Comsol script to loop through the Tb values in each small time step, but this is obviously not the smart way to go.
My gut feeling is that there is some fundamental issues not clear to me. It would be appreciated if someone could offer a little insight.
The problematic model with Tb defined as a constant function is attached below
I define a new function Tb = 374 to act as a boundary condition and got the same error message regarding Jacobian. If I define Tb as a constant, it works ok.
It looks like I can set up a Comsol script to loop through the Tb values in each small time step, but this is obviously not the smart way to go.
My gut feeling is that there is some fundamental issues not clear to me. It would be appreciated if someone could offer a little insight.
The problematic model with Tb defined as a constant function is attached below
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Just an update on some trouble shooting.
I define a new function Tb = 374 to act as a boundary condition and got the same error message regarding Jacobian. If I define Tb as a constant, it works ok.
It looks like I can set up a Comsol script to loop through the Tb values in each small time step, but this is obviously not the smart way to go.
My gut feeling is that there is some fundamental issues not clear to me. It would be appreciated if someone could offer a little insight.
The problematic model with Tb defined as a constant function is attached below
I define a new function Tb = 374 to act as a boundary condition and got the same error message regarding Jacobian. If I define Tb as a constant, it works ok.
It looks like I can set up a Comsol script to loop through the Tb values in each small time step, but this is obviously not the smart way to go.
My gut feeling is that there is some fundamental issues not clear to me. It would be appreciated if someone could offer a little insight.
The problematic model with Tb defined as a constant function is attached below
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Posted:
1 decade ago
It turns out the problem is that I need to explicitly write out the argument of the function to let COMSOL know it is a function. In another word, "f(t)" works, but not "f".