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Time dependant temperature at the boundary

Posted 27.01.2015, 19:37 GMT-5 MEMS & Nanotechnology, Heat Transfer & Phase Change, MEMS & Piezoelectric Devices, Materials, Modeling Tools & Definitions, Parameters, Variables, & Functions, Studies & Solvers Version 4.4, Version 5.0 10 Replies

Rogelio Hernandez Aguirre
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Hello,

I am new in COMSOL, so probably this question will be really naive for you, but I need to ask. I want to apply in one of the faces of my model a temperature that is changing with the time , what I have is a table of 20 set of datas

Temperature Time
20 0
32 300
50 500
55 642

And so on. However, I don't know how to introduce my data to change the boundary condition of the model according to my data, I am trying to use a Time dependent study but I don't know how.
I used a parametric sweep to change the temperature, but this option doesn't let me change the temperature according to the time.

I hope you can help me. I am sure is a really easy issue.

Rogelio
10 Replies Last Post 16.02.2015, 03:56 GMT-5
Lasse Murtomäki
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Posted: 10 years ago 28.01.2015, 13:39 GMT-5
Hi

It is possible by defining a piecewise function under Global --> Definitions --> Functions. Remember to add the unit for the argument and the function. Comsol gives the default name "pw1" for your function. Then, at the boundary condition box write pw1(t). I tried this and it works.

Good luck
Lasse
Hi It is possible by defining a piecewise function under Global --> Definitions --> Functions. Remember to add the unit for the argument and the function. Comsol gives the default name "pw1" for your function. Then, at the boundary condition box write pw1(t). I tried this and it works. Good luck Lasse
Rogelio Hernandez Aguirre
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Posted: 10 years ago 28.01.2015, 19:42 GMT-5
Thanks Lasse,

Works!. Now I am trying to do something different. Over my time dependent solution I want to use parameter sweep to change the value of one part of the geometry and try to know which is the best dimension of this parameter. However, I am getting this mistake when I click compute, after a while this message appears.

Error in sweep. Incompatible numerical evaluation for table.

do you know why is that? The parameter that I am changing is from 4 um to 8 um. pretty easy!

Regards

Rogelio
Thanks Lasse, Works!. Now I am trying to do something different. Over my time dependent solution I want to use parameter sweep to change the value of one part of the geometry and try to know which is the best dimension of this parameter. However, I am getting this mistake when I click compute, after a while this message appears. Error in sweep. Incompatible numerical evaluation for table. do you know why is that? The parameter that I am changing is from 4 um to 8 um. pretty easy! Regards Rogelio
Lasse Murtomäki
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Posted: 10 years ago 29.01.2015, 01:22 GMT-5
Please attach the model file (delete the results to reduce file size). I tried also that and had no problems.

Lasse
Please attach the model file (delete the results to reduce file size). I tried also that and had no problems. Lasse
Rogelio Hernandez Aguirre
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Posted: 10 years ago 04.02.2015, 12:53 GMT-5
Hi Lasse,

Attached you will find my model, some explanations about what I am doing:

1.- The parameter sweep of the thickness of my parylene layer is being done on the Auxiliary sweep option under Study Extensions tab. I am pretty sure that the error is related to some meshing issue.

2.- I am also including in my model temperature dependence properties, this was done with a interpolation function that is being called in the Materials property section for the corresponding property. However, I am getting a strange warning message : "Unexpected unit of input", although this message is not stopping the simulation I am worry about if this can lead to a wrong result. I am attaching a screenshot

I hope you can help me Lasse

Thanks in advance.
Hi Lasse, Attached you will find my model, some explanations about what I am doing: 1.- The parameter sweep of the thickness of my parylene layer is being done on the Auxiliary sweep option under Study Extensions tab. I am pretty sure that the error is related to some meshing issue. 2.- I am also including in my model temperature dependence properties, this was done with a interpolation function that is being called in the Materials property section for the corresponding property. However, I am getting a strange warning message : "Unexpected unit of input", although this message is not stopping the simulation I am worry about if this can lead to a wrong result. I am attaching a screenshot I hope you can help me Lasse Thanks in advance.
Lasse Murtomäki
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Posted: 10 years ago 04.02.2015, 15:00 GMT-5
You have to mesh the Parylene domains separately with custom parameters. I suggest minimum element size 0.1 um, maximum 1 um, resolution of narrow regions 4. Then ceramic and glass domains with, say, 1 um minimum, and finally the substrate with whatever size.

Your interpolation table int1 gives temperatures in degC, try K if it resolves the input unit problem, I am not sure.

Good luck
Lasse
You have to mesh the Parylene domains separately with custom parameters. I suggest minimum element size 0.1 um, maximum 1 um, resolution of narrow regions 4. Then ceramic and glass domains with, say, 1 um minimum, and finally the substrate with whatever size. Your interpolation table int1 gives temperatures in degC, try K if it resolves the input unit problem, I am not sure. Good luck Lasse
Rogelio Hernandez Aguirre
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Posted: 10 years ago 04.02.2015, 15:03 GMT-5
Thanks Lasse,

I will try with the meshing, thanks for your recommendation. Regarding the interpolation table, I already try changing the units and the warning message still there, looks like is not a error because I can run the model without the parametric sweep and get results.

Thanks a lot!
Thanks Lasse, I will try with the meshing, thanks for your recommendation. Regarding the interpolation table, I already try changing the units and the warning message still there, looks like is not a error because I can run the model without the parametric sweep and get results. Thanks a lot!
Lasse Murtomäki
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Posted: 10 years ago 04.02.2015, 16:02 GMT-5
Forget it, it made ca. 20,000,000 elements! Thin layers are very tricky to handle. Perhaps making Parylene as their own domains is not the way of doing it.
Forget it, it made ca. 20,000,000 elements! Thin layers are very tricky to handle. Perhaps making Parylene as their own domains is not the way of doing it.
Rogelio Hernandez Aguirre
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Posted: 10 years ago 04.02.2015, 16:31 GMT-5
If with domain is not possible, what else I can do?
If with domain is not possible, what else I can do?
Lasse Murtomäki
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Posted: 10 years ago 05.02.2015, 01:28 GMT-5
Use thin film or thin layer boundary condition where you now have Parylene coating. Without going deeply in your problem I cannot tell exactly how.

br
Lasse
Use thin film or thin layer boundary condition where you now have Parylene coating. Without going deeply in your problem I cannot tell exactly how. br Lasse
Dwekat
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Posted: 10 years ago 16.02.2015, 03:56 GMT-5
dont use the Auxiliary sweep from the study extension , try the parametric sweep study.
dont use the Auxiliary sweep from the study extension , try the parametric sweep study.

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