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-   -   Boundary condition again (http://www.cfd-online.com/Forums/openfoam-pre-processing/62242-boundary-condition-again.html)

evgenii November 26, 2005 09:07

Hi, everyone. I have some q
 
Hi, everyone.

I have some questions about boundary conditions.
1.Is it possible in boundary condition specify only 2 vector components? I mean, for example, E.x=0, E.y=0, E.z - has arbitrary value(there is no any conditions)
2. If I don't have any conditions can I write "calculated"? I've tried, but it didn't work. It returns error.
3. Can I specify boundary conditions in solver code?

Thank you
Eugene

hjasak November 26, 2005 09:40

1 The (x y z) decomposition do
 
1 The (x y z) decomposition does not make sense to me - you probably mean "normal to the boundary" and "tangential to it" when you think about it a bit more. There is a directionMidex b.c. and a more general form which allows you to have a separate mixed b.c. on each component (normal and tangential)

2 "Don't have any conditions" in the FVM probably means zeroGradient. Try that. "calculated" is for special cases, where the code genuinely does not know the b.c., e.g. when it's doing fv calculus: consider the b.c. on div(U) :-)

3. Yes and no. If you build teh field completely in the code, you can give it a list of b.c.-s, but hooking them up and setting parameters in most cases requires casting. If you read the field from a file, and you know what the b.c. is, you can cast it in the code and mess about with it.

Enjoy,

Hrv

evgenii November 26, 2005 10:04

Yes, I really mean that tangen
 
Yes, I really mean that tangential component is equal 0, and normal component doesn't have any conditions.

Yes, probably "zeroGradient" is something I need.

Thanks a lot, it's very useful fo me


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