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Different boundary conditions for dependent variables in PDE mode (coefficient form)
Posted Oct 11, 2012, 11:28 a.m. EDT Version 4.2 1 Reply
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Hi all,
I'm trying to solve a system of 4 PDEs on a rectangular box. My problem concerns the implementation of the boundary conditions. If I name my dependent variables, say u, v, w and p, then I want to implement dirichlet boundary conditions for the variables u, v and w. I found the Dirichlet boundary node and specified my conditions.
Nevertheless, for the variable p I need to implement something like: dp/dx = - (d^2 u)/(d x^2).
The zero flux condition doesn't seem right, especially because it applies to all variables (as far as I understand it).
So:
- Is there a way to specify the boundary conditions for each independent variable separately?
- What node has to be used to specify a condition as stated above?
It would be super awesome if someone could point me in the right direction.
Lothar
I'm trying to solve a system of 4 PDEs on a rectangular box. My problem concerns the implementation of the boundary conditions. If I name my dependent variables, say u, v, w and p, then I want to implement dirichlet boundary conditions for the variables u, v and w. I found the Dirichlet boundary node and specified my conditions.
Nevertheless, for the variable p I need to implement something like: dp/dx = - (d^2 u)/(d x^2).
The zero flux condition doesn't seem right, especially because it applies to all variables (as far as I understand it).
So:
- Is there a way to specify the boundary conditions for each independent variable separately?
- What node has to be used to specify a condition as stated above?
It would be super awesome if someone could point me in the right direction.
Lothar
1 Reply Last Post Oct 15, 2012, 8:22 a.m. EDT
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Posted:
1 decade ago
Hello, Lothar,
You don't need to include all the dependent variables in the same PDE. In the case you mention, perhaps you can include u, v, and w in one PDE (with particular boundary conditions) and the variable p in another PDE (with different boundary cond.). You can do this simply by adding new PDEs to your model. In order to couple the different PDE's, you can simply use some variables in the equations for other variables.
Bye,
Jesus.
You don't need to include all the dependent variables in the same PDE. In the case you mention, perhaps you can include u, v, and w in one PDE (with particular boundary conditions) and the variable p in another PDE (with different boundary cond.). You can do this simply by adding new PDEs to your model. In order to couple the different PDE's, you can simply use some variables in the equations for other variables.
Bye,
Jesus.