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helmholtz_square_simplified_domain_problem_engine.py
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Fri, May 3, 13:51

helmholtz_square_simplified_domain_problem_engine.py
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# Copyright (C) 2018 by the RROMPy authors
#
# This file is part of RROMPy.
#
# RROMPy 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.
#
# RROMPy 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 RROMPy. If not, see <http://www.gnu.org/licenses/>.
#
import numpy as np
import fenics as fen
from rrompy.utilities.base.types import paramVal
from rrompy.solver.fenics import fenZERO
from rrompy.hfengines.linear_problem.helmholtz_problem_engine import (
HelmholtzProblemEngine)
from rrompy.utilities.base import verbosityManager as vbMng
from rrompy.solver.fenics import fenics2Sparse
class HelmholtzSquareSimplifiedDomainProblemEngine(HelmholtzProblemEngine):
"""
Solver for square Helmholtz problems with parametric laplacian.
- \dxx u - mu_2**2 \dyy u - mu_1**2 * u = f in \Omega_mu = [0,\pi]^2
u = 0 on \partial\Omega
"""
def __init__(self, kappa:float, theta:float, n:int,
mu0 : paramVal = [12. ** .5, 1.],
degree_threshold : int = np.inf, verbosity : int = 10,
timestamp : bool = True):
super().__init__(mu0 = mu0, degree_threshold = degree_threshold,
verbosity = verbosity, timestamp = timestamp)
self._affinePoly = True
self.nAs = 3
self.npar = 2
self.rescalingExp = [2., 2.]
pi = np.pi
mesh = fen.RectangleMesh(fen.Point(0, 0), fen.Point(pi, pi),
3 * n, 3 * n)
self.V = fen.FunctionSpace(mesh, "P", 1)
c, s = np.cos(theta), np.sin(theta)
x, y = fen.SpatialCoordinate(mesh)[:]
self.forcingTerm = [fen.cos(kappa * (c * x + s * y)),
fen.sin(kappa * (c * x + s * y))]
def buildA(self):
"""Build terms of operator of linear system."""
if self.thAs[0] is None: self.thAs = self.getMonomialWeights(self.nAs)
if self.As[0] is None:
vbMng(self, "INIT", "Assembling operator term A0.", 20)
DirichletBC0 = fen.DirichletBC(self.V, fenZERO,
self.DirichletBoundary)
a0Re = fen.dot(self.u.dx(0), self.v.dx(0)) * fen.dx
self.As[0] = fenics2Sparse(a0Re, {}, DirichletBC0, 1)
vbMng(self, "DEL", "Done assembling operator term.", 20)
if self.As[1] is None:
vbMng(self, "INIT", "Assembling operator term A1.", 20)
DirichletBC0 = fen.DirichletBC(self.V, fenZERO,
self.DirichletBoundary)
nRe, nIm = self.refractionIndex
n2Re, n2Im = nRe * nRe - nIm * nIm, 2 * nRe * nIm
parsRe = self.iterReduceQuadratureDegree(zip([n2Re],
["refractionIndexSquaredReal"]))
parsIm = self.iterReduceQuadratureDegree(zip([n2Im],
["refractionIndexSquaredImag"]))
a1Re = - n2Re * fen.dot(self.u, self.v) * fen.dx
a1Im = - n2Im * fen.dot(self.u, self.v) * fen.dx
self.As[1] = (fenics2Sparse(a1Re, parsRe, DirichletBC0, 0)
+ 1.j * fenics2Sparse(a1Im, parsIm, DirichletBC0, 0))
vbMng(self, "DEL", "Done assembling operator term.", 20)
if self.As[2] is None:
vbMng(self, "INIT", "Assembling operator term A2.", 20)
DirichletBC0 = fen.DirichletBC(self.V, fenZERO,
self.DirichletBoundary)
a2Re = fen.dot(self.u.dx(1), self.v.dx(1)) * fen.dx
self.As[2] = fenics2Sparse(a2Re, {}, DirichletBC0, 0)
vbMng(self, "DEL", "Done assembling operator term.", 20)

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