Additional diffusion terms in PDE

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Fengtao Bai

Fengtao Bai

June 9, 2017 2:16pm UTC

Additional diffusion terms in PDE

Hi all,

I am trying to figure out if it is possible to have two diffusion terms in any PDE equations that COMSOL provides. So far it does not seem to be a simple task.

Is there a way to define a new PDE from scratch other than using predefined format in COMSOL?

Any input is appreciated.


Best,

Fengtao

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Jeff Hiller

Jeff Hiller
COMSOL Employee
USA
Moderator

June 13, 2017 9:28pm UTC in response to Fengtao Bai

Re: Additional diffusion terms in PDE

Hello Fengtao,

Both approaches (i.e. adding terms to an existing physics interface on the one hand, and setting up your own PDE entirely from scratch on the other hand) are possible and both are documented in the COMSOL Multiphysics Reference Manual, version 5.3, Chapter 16. All manuals are found under File > Help > Documentation.

You will also find several tutorials on the topic of equation-based modeling in the Application Libraries.
I hope this helps you get started.
Best regards,
Jeff

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Fengtao Bai

Fengtao Bai

June 16, 2017 5:08pm UTC in response to Jeff Hiller

Re: Additional diffusion terms in PDE


Hello Fengtao,

Both approaches (i.e. adding terms to an existing physics interface on the one hand, and setting up your own PDE entirely from scratch on the other hand) are possible and both are documented in the COMSOL Multiphysics Reference Manual, version 5.3, Chapter 16. All manuals are found under File > Help > Documentation.

You will also find several tutorials on the topic of equation-based modeling in the Application Libraries.
I hope this helps you get started.
Best regards,
Jeff


Hi Jeff,

Appreciate it! I went through the document and tried a couple of approaches in COMSOL but it seems that I cannot add additional terms based on General Form and Factor Form PDEs.

However, the weak form PDE is interesting. The problems is that weak form PDE only deals with space domain and the time domain (for transient problems) cannot be implemented.

Any idea or comments?


Best,

Fengtao


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Jeff Hiller

Jeff Hiller
COMSOL Employee
USA
Moderator

June 19, 2017 1:08pm UTC in response to Fengtao Bai

Re: Additional diffusion terms in PDE

Hello Fengtao,
Maybe I misunderstand your last post. It is definitely possible to set up time-dependent equations in the weak form (and in the general form and in the coefficient form - there is no factor form).
Should you need further assistance, please contact COMSOL's technical support team: support@comsol.com .
Best regards,
Jeff

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Fengtao Bai

Fengtao Bai

June 19, 2017 1:55pm UTC in response to Jeff Hiller

Re: Additional diffusion terms in PDE

Appreciate it Jeff

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