[Hedge] boundary condition

[Andreas Kloeckner]

Hi Islam,

On Tue, 14 Dec 2010 13:50:43 +0100, "Islam El Salawi" <islamelsalawi at gmx.de> wrote:
> watching wing.py script, I found:
> 
> fvi2fm = mesh.face_vertex_indices_to_face_marker
> 
> in make_wingmesh(). "fvi2fm" is a variable of type "dict" in which
> frozensets of vertex indices are assigned to a specific integer. This
> integer represents a boundary condition. In this dictionary "fvi2fm"
> stands the following example:
> 
> frozenset([2475, 3445, 1406]): 1000
> 
> with the specified frozenset of vertex indices and the allocated
> integer. My question is, why are there three vertex indices?

As you can see, fvi2fm stands for 'face vertex indices -to- face
marker', and that's precisely what's being mapped. The frozenset maps a
set of vertices adjoining a face (in any order, hence a set) to a
numerical face marker, which can then be mapped to a string boundary tag
(as Scott explained a while ago) as hedge requires it.

> Is it possible to create a dict with frozensets of all "noslip" vertex
> indices and allocate the boundary condition to it, like
> 
> wall=[0,1,4,5......2348,5990]
> inflow=[35,46,57,....,134]
> dict({frozenset(wall):1000,frozenset(inflow):2})
> 
> "wall" is a list with all nodes or vertices of an area with special
> interest. inflow is self-explanatory.

Not quite--you need sets of the vertices of each face. But otherwise
your plan sounds fine.

HTH, and sorry for the delay,
Andreas
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