# Error with setting the boundary condition

Dear all

I am trying to solve Poisson equation on a contraction step problem. I get an error to set dirichlet boundary condition at different boundaries.

Here is the part of the code:
######################################################################################################

from ngsolve import *
import matplotlib.pyplot as plt
import numpy as np
from netgen.geom2d import SplineGeometry
ngsglobals.msg_level =2

# %% Geometry generation (points definition)

geo = SplineGeometry()
p1 = geo.AppendPoint (0,0)
p2 = geo.AppendPoint (3,0)
p3 = geo.AppendPoint (3,0.1)
p4 = geo.AppendPoint (2,0.1)
p5 = geo.AppendPoint (2,1)
p6 = geo.AppendPoint (0,1)

geo.Append ([“line”, p1, p2],bc=1) # bottom
geo.Append ([“line”, p2, p3],bc=2) # outlet
geo.Append ([“line”, p3, p4],bc=3) # horizontal
geo.Append ([“line”, p4, p5],bc=4) # vertical
geo.Append ([“line”, p5, p6],bc=5) # top
geo.Append ([“line”, p6, p1],bc=6) # Inlet

mesh = geo.GenerateMesh (maxh=0.1)

fes = H1(mesh, order=2, dirichlet=[1,2])

###################################

And this is the error message:

init(): incompatible constructor arguments. The following argument types are supported:

1. ngsolve.comp.H1(mesh: ngsolve.comp.Mesh, **kwargs)

Invoked with: <netgen.libngpy._meshing.Mesh object at 0x000001722D060BF0>; kwargs: order=2, dirichlet=[1, 2

Hi omar,

the FE space needs a ngsolve mesh (rather than a netgen mesh). You can fix it by making the netgen mesh a ngsolve mesh:

mesh = Mesh(geo.GenerateMesh (maxh=0.1))

Best wishes, Henry