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State-Space reduction

Posted Nov 7, 2022, 10:16 p.m. EST General, Studies & Solvers, Physics Interfaces 4 Replies

Andebet Zegeye
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Hello, I have a quick question, Is it possible to perform State-Space reduction in COMSOL and export the matrix? Thank You

4 Replies Last Post Nov 9, 2022, 2:52 p.m. EST
Remi Magnard COMSOL Employee

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Posted: 2 years ago Nov 8, 2022, 2:44 a.m. EST
Updated: 2 years ago Nov 8, 2022, 3:40 a.m. EST

Hi,

you have two options to export your COMSOL model to a state-space system: add a State Space node in the solver configuration or create a modal reduced-order model (ROM).

Which one to use depends on the problem you want to solve. I would recommend you to use a ROM as you have full control on the reduction; however, it requires that the physics interface supports an eigenvalue/eigenfrequency study. The first option (using a State Space node) can be used for any physics interface but does not provide any reduction; the size of the exported system is the same as the full model.

To extract the matrices either use a Matrix Evaluation node in the Model Builder or use LiveLink for MATLAB to extract them at the MATLAB prompt. To read more about state-space systems, I can recommend you to look at the COMSOL Multiphysics Reference Manual and the LiveLink for MATLAB User's Guide.

I hope this will help!

Hi, you have two options to export your COMSOL model to a state-space system: add a State Space node in the solver configuration or create a modal reduced-order model (ROM). Which one to use depends on the problem you want to solve. I would recommend you to use a ROM as you have full control on the reduction; however, it requires that the physics interface supports an eigenvalue/eigenfrequency study. The first option (using a State Space node) can be used for any physics interface but does not provide any reduction; the size of the exported system is the same as the full model. To extract the matrices either use a Matrix Evaluation node in the Model Builder or use LiveLink for MATLAB to extract them at the MATLAB prompt. To read more about state-space systems, I can recommend you to look at the COMSOL Multiphysics Reference Manual and the LiveLink for MATLAB User's Guide. I hope this will help!
Andebet Zegeye
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Posted: 2 years ago Nov 8, 2022, 2:10 p.m. EST

Thank You Remi, I am using heat transfer in solid pysics, just to confirm, if i use ROM, will I be able to export the matrices from the reduced model?

Thank You Remi, I am using heat transfer in solid pysics, just to confirm, if i use ROM, will I be able to export the matrices from the reduced model?
Remi Magnard COMSOL Employee

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Posted: 2 years ago Nov 9, 2022, 3:03 a.m. EST

Yes, with the Heat Transfer module you can compute eigenvalue for heat transfer in solid, and so generate a modal reduced model to extract state-space matrices.

Yes, with the Heat Transfer module you can compute eigenvalue for heat transfer in solid, and so generate a modal reduced model to extract state-space matrices.
Andebet Zegeye
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Posted: 2 years ago Nov 9, 2022, 2:52 p.m. EST

Thank you Remi.

Thank you Remi.

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