CODEWITHSUNDEEP
pythonmeshfipy
Cjdkwq
Cjdkwq

Reputation: 13

Specifying a custom Fipy boundary condition of an "L" shaped geometry

I want to solve a heat diffusion problem with an "L-shape" geometry, defined by the code below:

from fipy import CellVariable, Gmsh2D, TransientTerm, DiffusionTerm
from fipy import Matplotlib2DViewer, Viewer
from fipy.tools import numerix

cellSize_1 = 0.05
mesh = Gmsh2D('''
              cellSize = %(cellSize_1)g;
              Point(1) = {0, 0, 0, cellSize};
              Point(2) = {0, 5, 0, cellSize};
              Point(3) = {1, 5, 0, cellSize};
              Point(4) = {1, 1, 0, cellSize};
              Point(5) = {4, 1, 0, cellSize};
              Point(6) = {4, 0, 0, cellSize};
              Line(7) = {1, 2};
              Line(8) = {2, 3};
              Line(9) = {3, 4};
              Line(10) = {4, 5};
              Line(11) = {5, 6};
              Line(12) = {6, 1};
              Physical Surface("Top") = {8};
              Physical Surface("Inner") = {9, 10};
              Physical Surface("Right") = {11};
              Physical Surface("Inner") = {12, 7};
              Line Loop(13) = {7, 8, 9, 10, 11, 12};
              Plane Surface(14) = {13};
              ''' % locals()) # doctest: +GMSH

# Using this mesh, we can construct a solution variable

phi = CellVariable(name = "solution variable",
                   mesh = mesh,
                   value = 0.) # doctest: +GMSH

# We can now create a Viewer to see the mesh

viewer = None
from builtins import input
if __name__ == '__main__':
    try:
        viewer = Viewer(vars=phi, datamin=-1, datamax=3)
        viewer.plotMesh()

    except:
        print("Unable to create a viewer for an irregular mesh (try "+
              "Matplotlib2DViewer or MayaviViewer)")

Now I want to define the "Top" and "Right" boundaries as Dirichlet boundaries with constant values as 1 and 0. And I want define the "Inner" and "Right" as Neumann boundaries with flux equal to 0. How should I go about setting up the constraints? I used:

phi.constrain(1, where = mesh.Front)
phi.constrain(0, where = mesh.Top)
phi.faceGrad.constrain(0 * mesh.faceNormals, where = mesh.Inner)
phi.faceGrad.constrain(0 * mesh.faceNormals, where = mesh.Outter)

But all I got was "AttributeError: 'Gmsh2D' object has no attribute 'Front'" error. How can I fix this? Thank you very much.

Upvotes: 1

Views: 194

Answers (1)

jeguyer
jeguyer

Reputation: 2484

The use of Gmsh-defined cells and faces is demonstrated in the docstring for Gmsh2D. Specifically, you want:

mesh.physicalFaces["Front"]

etc., which should be defined in your Gmsh script as a Physical Line, not a Physical Surface.

Upvotes: 1

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