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Error in Interpolation Function

Posted Sep 24, 2021, 1:10 p.m. EDT Fluid & Heat, Heat Transfer 4 Replies

Andrew Holmes
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Hello All,

I am currently using an interpolation function, defined using a .txt file, as an time-dependent inlet temperature profile for the 'Heat Transfer in Pipes' interface.

The model successfully calls the function, however, there is a small error in what is called by the input function and what can be measured in the Results section, using a Point Evaluation at the inlet. The error is typically small, fluctuating around plus/minus 0.03 C, except at the beginning and end of the time range where it can reach values of close to plus/minus 0.2 C.

If anyone knows what may be causing this discrepancy, or how to minimize it, that would be greatly appreciated.

Thank you! Andrew

4 Replies Last Post Dec 28, 2021, 1:04 a.m. EST
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Hello Andrew Holmes

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Hyucksu Choi
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Posted: 3 years ago Dec 27, 2021, 3:37 a.m. EST

Hi Andrew Holmes.

Have you soved your problem? If so, could you share your method? I have the exact same problem for my ewbe model.

Hi Andrew Holmes. Have you soved your problem? If so, could you share your method? I have the exact same problem for my ewbe model.
Hyucksu Choi
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Posted: 3 years ago Dec 27, 2021, 3:38 a.m. EST

Hi Andrew Holmes.

Have you soved your problem? If so, could you share your method? I have the exact same problem for my ewbe model.

Hi Andrew Holmes. Have you soved your problem? If so, could you share your method? I have the exact same problem for my ewbe model.
Robert Koslover Certified Consultant
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Posted: 3 years ago Dec 27, 2021, 11:41 a.m. EST
Updated: 3 years ago Dec 27, 2021, 11:43 a.m. EST

You mentioned that this difference was seen in the Results. Comsol computed quantities can vary depending on the mesh, discretization, etc. I'm willing to bet that if you modify the mesh, the time-step, the discretization, etc., that you will see that the "discrepancy" in question will also vary somewhat. In other words, this is probably just a byproduct of your using a numerical model with discretized space and time.

-------------------
Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
You mentioned that this difference was seen in the *Results*. Comsol computed quantities can vary depending on the mesh, discretization, etc. I'm willing to bet that if you modify the mesh, the time-step, the discretization, etc., that you will see that the "discrepancy" in question will also vary somewhat. In other words, this is *probably* just a byproduct of your using a *numerical* model with *discretized* space and time.
Hyucksu Choi
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Posted: 3 years ago Dec 28, 2021, 1:04 a.m. EST
Updated: 3 years ago Dec 28, 2021, 1:04 a.m. EST

I interpolated into the model which the txt data exported. So I guess this is not the case. Uploaded the file I tested for this problem.

I interpolated into the model which the txt data exported. So I guess this is not the case. Uploaded the file I tested for this problem.

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