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Inverse Calculation of Thermal Conductivity Using the Optimization Module

Posted 07.06.2012, 17:40 GMT-4 Heat Transfer & Phase Change, Modeling Tools & Definitions, Parameters, Variables, & Functions, Studies & Solvers Version 4.2a 10 Replies

Tolga Y. Ozudogru
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Dear All,

I created a 3D borehole heat exchanger model. It includes 'Heat Transfer in Solids' and 'Thin Conductive Shell' nodes. After getting the velocity profile of the fluid using stationary analysis, I solve the working of the heat exchanger using time-dependent analysis by applying an added temperature difference to the inlet (inlet = outlet + delta_T(t)).

So far, this model works. However, I also have experimental field data for the inlet and outlet temperature measurements and the model output differs from the field data. I am looking for a way to use the optimization module to alter the thermal conductivity of the soil to match the experimental data with the model output.

I wonder if it is possible. If yes, could you please guide me at least where to start? I tried to use the optimization module by adding control variable field, pointwise inequality constraint and least squares objective (time+value columns) but I couldn't make it to work.

The inside of the pipes in my model are empty, they are modeled by thin conductive shell elements and thus, my inlet/outlet are defined as edges. I also included a screenshot of my geometry.

Thanks in advance.
--
Tolga
10 Replies Last Post 02.07.2012, 17:02 GMT-4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 08.06.2012, 03:46 GMT-4
Hi

with the optimisation module you can build complex optimisation chemes, but if it is "just" to fit a single parameter you can do it as well via an ODE, you add the variable as a dependet variable, load in the experimental results and use the difference between the simulation and the data (squared to easier search for the minimum) as driver for your optimisation variable

Try it out on a simple model first, I believ there is at least such a model in HT model library somewhere

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Good luck
Ivar
Hi with the optimisation module you can build complex optimisation chemes, but if it is "just" to fit a single parameter you can do it as well via an ODE, you add the variable as a dependet variable, load in the experimental results and use the difference between the simulation and the data (squared to easier search for the minimum) as driver for your optimisation variable Try it out on a simple model first, I believ there is at least such a model in HT model library somewhere -- Good luck Ivar
Tolga Y. Ozudogru
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Posted: 1 decade ago 14.06.2012, 13:30 GMT-4
Thank you Ivar for your valuable comments.

I will be needing optimization for several parameters, supposedly 4 to 8. I tried to find a simple model in the model library which fits the desired parameter(s) with respect to experimental data but couldn't find any. Do you know where can I find a simple example model for optimization?

Thanks.

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Tolga
Thank you Ivar for your valuable comments. I will be needing optimization for several parameters, supposedly 4 to 8. I tried to find a simple model in the model library which fits the desired parameter(s) with respect to experimental data but couldn't find any. Do you know where can I find a simple example model for optimization? Thanks. -- Tolga
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 14.06.2012, 13:51 GMT-4
Hi

I do not really know about a model library with many variables. You can take a look at my Model Exchange "Zernike development" example its a 4.2a model, now I cannot remember if I made it with the optimisation or only as ODEs. Have a try

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Good luck
Ivar
Hi I do not really know about a model library with many variables. You can take a look at my Model Exchange "Zernike development" example its a 4.2a model, now I cannot remember if I made it with the optimisation or only as ODEs. Have a try -- Good luck Ivar
Tolga Y. Ozudogru
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Posted: 1 decade ago 14.06.2012, 13:59 GMT-4
Hi Ivar,

Thanks again. I will check your model.

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Tolga
Hi Ivar, Thanks again. I will check your model. -- Tolga
Tolga Y. Ozudogru
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Posted: 1 decade ago 15.06.2012, 13:28 GMT-4
Hi Ivar,

I checked your model and also a model in the model library -material_property_fitting- (if it is not there, update your library). I have successfully obtained the optimization of the parameters.

The example model in the library is also good for a start.

Thanks again.

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Tolga
Hi Ivar, I checked your model and also a model in the model library -material_property_fitting- (if it is not there, update your library). I have successfully obtained the optimization of the parameters. The example model in the library is also good for a start. Thanks again. -- Tolga
Wane Birane
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Posted: 1 decade ago 26.06.2012, 17:27 GMT-4
Hello Tolga,

Can you explain how you made it? I want to do an optimization of thermal conductivity for a 2D model in COMSOL, i'm a beginner, so if you have time to explain the method it will be great.

Thanks.
Hello Tolga, Can you explain how you made it? I want to do an optimization of thermal conductivity for a 2D model in COMSOL, i'm a beginner, so if you have time to explain the method it will be great. Thanks.
Jeff Hiller COMSOL Employee

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Posted: 1 decade ago 26.06.2012, 17:34 GMT-4
Hi Tolga,
You may find this model interesting as well for reverse modeling of a material property:
www.comsol.com/showroom/gallery/4410/
Best of luck in your work,
JF
Hi Tolga, You may find this model interesting as well for reverse modeling of a material property: http://www.comsol.com/showroom/gallery/4410/ Best of luck in your work, JF
Tolga Y. Ozudogru
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Posted: 1 decade ago 26.06.2012, 17:55 GMT-4
Hi Wane,

I am using COMSOL 4.2a. There is a tutorial model in the model library which you can study in order to build your own model. It does parameter fitting for thermal conductivity and specific heat capacity on a 1-D geometry using heat transfer and optimization modules.

Browse the material library and look for the model named "material_property_fitting". It is under Optimization Module / Tutorial Models. If it is not there, update your model library to download it.

Jean-Francois, thank you for the heads up on the other model.

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Tolga
Hi Wane, I am using COMSOL 4.2a. There is a tutorial model in the model library which you can study in order to build your own model. It does parameter fitting for thermal conductivity and specific heat capacity on a 1-D geometry using heat transfer and optimization modules. Browse the material library and look for the model named "material_property_fitting". It is under Optimization Module / Tutorial Models. If it is not there, update your model library to download it. Jean-Francois, thank you for the heads up on the other model. -- Tolga
Wane Birane
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Posted: 1 decade ago 28.06.2012, 03:22 GMT-4
Thanks Tolga for your answer.

So, i tried to update the model library, but i didn't find that model. Can you attach the file with the pdf model?

Thanks.
Thanks Tolga for your answer. So, i tried to update the model library, but i didn't find that model. Can you attach the file with the pdf model? Thanks.
Tolga Y. Ozudogru
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Posted: 1 decade ago 02.07.2012, 17:02 GMT-4
Hi Wane,

I am sorry but it could be inappropriate for me to send one of COMSOL's own models here. Please ask a COMSOL employee for that.

However, the model should be in the updated model library / Optimization branch. Are you sure you have the optimization module?

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Tolga
Hi Wane, I am sorry but it could be inappropriate for me to send one of COMSOL's own models here. Please ask a COMSOL employee for that. However, the model should be in the updated model library / Optimization branch. Are you sure you have the optimization module? -- Tolga

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