boundary condition: alpha*dp/dt = u&n
normally, on wall boundaries for example, we must guarantee:
and the inner product has to be zero.
On a specific patch, I impose a diriclet boundary condition for the pressure.
For the velocity, I want to have:
A slip wall uses in the end the basicSymmetryFvPatchField method, resulting in 0 = u&n
and nf is normal patch face vector pointing outward with
Then evaluate returns a vector
((1 1) + transform([1 0;0 1] - [0 0 ;0 2],(1 1)])/2
n&U is zero, hence 0=1*0+0*0
0 = U&n is fullfilled.
But how can
Any help will be appreciated!
After a long night... direction mixed boundary condition approach, maybe?!
here my update, maybe things become clearer:
since I want to impose
where I found directionMixedFvPatchField.C
If I understand it right:
For a vector (like in my case it is velocity U), this boundary condition is decomposed into the normal and tangential component.
I have to set three reference values for that boundary condition (good description under http://www.cfd-online.com/Forums/ope...tml#post316165:
1) refValue = which will be the value on face in normal direction
2) refGradient = will be enforced in the patch tangential direction
3) valueFraction = which is the symmetrical Tensor, which I have to define for transformation purposes
I think this b.c. is a good starting point for manipulating my boundary condition for U...
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