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"This demo program demonstrates various algorithms for mesh smoothing."
# Copyright (C) 2010, 2015 Anders Logg
#
# This file is part of DOLFIN.
#
# DOLFIN is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# DOLFIN is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with DOLFIN. If not, see <http://www.gnu.org/licenses/>.
#
# First added: 2010-03-02
# Last changed: 2010-05-11
from dolfin import *
import matplotlib.pyplot as plt
parameters["refinement_algorithm"] = "plaza"
# Create rectangular mesh
mesh = RectangleMesh(Point(0.0, 0.0), Point(2.4, 0.4), 60, 10)
# Define a circular hole
center = Point(0.2, 0.2)
radius = 0.05
class Hole(SubDomain):
def inside(self, x, on_boundary):
r = sqrt((x[0] - center[0])**2 + (x[1] - center[0])**2)
return r < 1.5*radius # slightly larger
def snap(self, x):
r = sqrt((x[0] - center[0])**2 + (x[1] - center[1])**2)
if r < 1.5*radius:
x[0] = center[0] + (radius / r)*(x[0] - center[0])
x[1] = center[1] + (radius / r)*(x[1] - center[1])
# Mark hole and extract submesh
hole = Hole()
sub_domains = MeshFunction("size_t", mesh, mesh.topology().dim())
sub_domains.set_all(0)
hole.mark(sub_domains, 1)
mesh = SubMesh(mesh, sub_domains, 0)
mesh.snap_boundary(hole)
# Refine and snap mesh
plt.figure()
plot(mesh, title="Mesh 0")
num_refinements = 3
for i in range(num_refinements):
# Mark cells for refinement
markers = MeshFunction("bool", mesh, mesh.topology().dim())
markers.set_all(False)
for cell in cells(mesh):
if cell.midpoint().distance(center) < 2*radius:
markers[cell.index()] = True
# Refine mesh
mesh = refine(mesh, markers)
# Snap boundary
mesh.snap_boundary(hole)
# Plot mesh
plt.figure()
plot(mesh, title=("Mesh %d" % (i + 1)))
plt.show()
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