Question on how to display selected faces of few cells

[RadheChandu]

Hello fipyTeam,

I am working on a problem in which I need to apply flux boundary conditions on few internal cells. I am able to select the cells. But now I want to select their exterior faces and also would like to see in Viewer, if I did select the correct cells and Faces. Can someone please help me with this.

This is the sample code.

`
from fipy import CellVariable, Grid3D, Viewer, numerix, FaceVariable

mesh = Grid3D(.1,.1,.1, 40, 40, 10)

mesh = mesh + ((-2,), (-2,), (-1,))

alp = CellVariable(mesh, value = 0.)

X, Y, Z = mesh.cellCenters

radius = 0.5

selected = X2 + Y2 < radius**2

alp.setValue(1., where = selected)

viewer = Viewer(vars = alp)`

I was able to check that I selected the correct cells. but how to visualize the selected faces.

I tried something like this..

`
allFaces = mesh.cellFaceIDs.data

selectedCellFaces = numerix.unique(allFaces[:, selected]).flatten()
unselectedCellFaces = numerix.unique(allFaces[:, numerix.invert(selected)]).flatten()

selectedExteriorFaces = numerix.intersect1d(selectedCellFaces, unselectedCellFaces)

SelectFaces = numerix.zeros(mesh.numberOfFaces, dtype = bool)

SelectFaces[selectedExteriorFaces] = True

beta = FaceVariable(mesh, value = 0.)

beta.setValue(10, where = SelectFaces)

viewer = Viewer(vars = beta)`

But its showing cellcenters of mesh and face values as points. Is there any better way of doing this?

[guyer]

I'm afraid we don't have anything that will improve the visualization. Visualization of FaceVariables is just not something we've prioritized. For that matter, we haven't spent a ton of time developing general tools for 3D visualization, because it's just so problem-specific. On the bright side, the full power of mayavi is at your disposal with a custom MayaviDaemon, as illustrated in examples.cahnHilliard.sphere. You're on your own figuring out what to tell mayavi, though.

My recommendation, though, is to use Gmsh to define the boundary explicitly, akin to what's shown in the Gmsh2D documentation. Then you can be confident that the boundary faces are where you want them and can access them easily with my_mesh.physicalFaces["my_boundary_label"].

[RadheChandu]

Thank you for your reply.. I will look at the sources and will try to figure out something..