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'Set' of GridFunction do not work correctly for surface mesh.

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2 years 10 months ago #3788 by yzz
'Set' of GridFunction do not work correctly for surface mesh. was created by yzz
Hi,

When I set a grid function defined on a surface, the results seem wrong. See the following code and output.

When I set the parameter to `BND`, the values of h_n are still all zeros.
Code:
from ngsolve import * from netgen.csg import * from netgen.meshing import MeshingStep # from ngsolve.webgui import Draw geo = CSGeometry() sphere = Sphere(Pnt(0, 0, 0), 1).bc('inner') left = Plane(Pnt(0.75, 0, 0), Vec(-1, 0, 0)) fsphere = sphere*left geo.AddSurface(sphere, fsphere) geo.NameEdge(sphere, fsphere, 'boundary') mesh = Mesh(geo.GenerateMesh(maxh=0.3)) # Draw(mesh) print_vec = lambda u: print([_ for _ in u.vec.data]) V_H = H1(mesh) print(V_H.FreeDofs()) h = CoefficientFunction(1) h_n = GridFunction(V_H) h_n.Set(h) print_vec(h_n) h_n.Set(h, BND) print_vec(h_n) h_n.Set(h, BBND) print_vec(h_n)


Code:
0: 1111111111111111111111111111 [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0] [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0] [1.0, 1.0, 1.0, 1.0, 0.9999999999999999, 1.0, 1.0, 1.0, 1.0, 0.9999999999999998, 1.0, 0.9999999999999999, 1.0, 1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
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2 years 10 months ago #3789 by mneunteufel
Replied by mneunteufel on topic 'Set' of GridFunction do not work correctly for surface mesh.
Hi,

to set a function on the whole boundary, which is not marked explicitly as Dirichlet boundary, you have to use the syntax
Code:
h_n.Set(h, definedon=mesh.Boundaries(".*"))

When setting explicitly the whole boundary as Dirichlet boundary then the code works
Code:
V_H = H1(mesh, dirichlet=".*") ... h_n.Set(h, BND)

Best,
Michael
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2 years 10 months ago #3791 by yzz
Replied by yzz on topic 'Set' of GridFunction do not work correctly for surface mesh.
Thanks, Michael.

Best wishes,
Zongze Yang
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