2D Geometry with partly shared edge

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1

Hello,

we would like to build a 2D Geometry (for example two nested rectangles) that represent one half of a symmetric problem, so the inner rectangle is completely shifted to the edge of the sourounding rectangle. At that moment we cannot mesh the geometry.
How could we implement this?

from netgen.geom2d import *
from ngsolve import *

geo = SplineGeometry()
geo.AddRectangle ( (0,0), (2,2), bcs=["b","r","t","l"], leftdomain=1)
geo.AddRectangle ( (0,0.5), (1,1.5), bcs=["b2","r2","t2","l2"], leftdomain=2, rightdomain=1)
geo.SetMaterial (1, "outer")
geo.SetMaterial (2, "inner")
mesh = Mesh(geo.GenerateMesh(maxh=0.1))
2

Hi creativeworker,

to construct such a mesh you need to specify the points and lines by hand

[code]from netgen.geom2d import *
from ngsolve import *

geo = SplineGeometry()
pnts = [ (0,0), (2,0), (2,2), (0,2), (0,1.5), (0,0.5), (1,0.5), (1,1.5)]
pind = [ geo.AppendPoint(*pnt) for pnt in pnts ]

geo.Append([‘line’,pind[0],pind[1]],leftdomain=1,rightdomain=0,bc=“b”)
geo.Append([‘line’,pind[1],pind[2]],leftdomain=1,rightdomain=0,bc=“r”)
geo.Append([‘line’,pind[2],pind[3]],leftdomain=1,rightdomain=0,bc=“t”)
geo.Append([‘line’,pind[3],pind[4]],leftdomain=1,rightdomain=0,bc=“l”)
geo.Append([‘line’,pind[4],pind[5]],leftdomain=2,rightdomain=0,bc=“l”)
geo.Append([‘line’,pind[5],pind[0]],leftdomain=1,rightdomain=0,bc=“l”)
geo.Append([‘line’,pind[5],pind[6]],leftdomain=2,rightdomain=1,bc=“b2”)
geo.Append([‘line’,pind[6],pind[7]],leftdomain=2,rightdomain=1,bc=“r2”)
geo.Append([‘line’,pind[7],pind[4]],leftdomain=2,rightdomain=1,bc=“t2”)

geo.SetMaterial (1, “outer”)
geo.SetMaterial (2, “inner”)
mesh = Mesh(geo.GenerateMesh(maxh=0.1))[/code]

Best,
Michael