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One boundary with two boundary conditions (Neumann and Dirichlet)

Posted 26 set 2012, 05:11 GMT-4 Modeling Tools & Definitions, Parameters, Variables, & Functions, Studies & Solvers Version 4.2, Version 4.3b 3 Replies

Thanh Lem
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Please help me to understand about this issue.

I have a system of two PDE equations with two variables (u1, u2) need to be solved in General Form.

On a boundary 1, for example, I set up a Neumann boundary condition:
-n.Γ1 = f1
-n.Γ2 = f2

And then, still on the boundary 1, I set up one more Dirichlet boundary condition:
u1=f3 (Prescribed value of u1)
u2=f4 (Prescribed value of u2)

And I saw Comsol let me know that, the two conditions contribute together. So, which condition in two condition above will perform (affect to u2 on the boundary 1) in my model? (Both of them?)

Thank you so much for your help.

Best regards,
3 Replies Last Post 16 apr 2015, 09:44 GMT-4
COMSOL Moderator

Hello Thanh Lem

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Adrián Lara
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Posted: 1 decade ago 28 feb 2013, 05:17 GMT-5
Hi!

I guess the boundary condition you implement depends on that that you are trying to model, right?
Hi! I guess the boundary condition you implement depends on that that you are trying to model, right?
Marco Zanoni
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Posted: 1 decade ago 23 ott 2013, 12:20 GMT-4
Hi,

I'm trying to apply a constant heat flux in the energy equation,

for example,

-n(Gamma)=g where g=41000[W/m^2],

but I'm not getting good results. Do you know if I just put g=41000[W/m^2] is correct?

Thanks.

Marco
Hi, I'm trying to apply a constant heat flux in the energy equation, for example, -n(Gamma)=g where g=41000[W/m^2], but I'm not getting good results. Do you know if I just put g=41000[W/m^2] is correct? Thanks. Marco
Thierry Meier
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Posted: 10 years ago 16 apr 2015, 09:44 GMT-4
Hello Marco,

I am trying to solve a similar problem. I would like to specify both on one boundary (heat flux and temperature)
Did you find a way to get around the overwriting problem?

Thierry
Hello Marco, I am trying to solve a similar problem. I would like to specify both on one boundary (heat flux and temperature) Did you find a way to get around the overwriting problem? Thierry

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