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helmholtz_problem_engine.py
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helmholtz_problem_engine.py
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# Copyright (C) 2018-2020 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 fenics as fen
from .laplace_base_problem_engine import LaplaceBaseProblemEngine
from rrompy.solver.fenics import fenZERO, fenONE, fenics2Sparse
from rrompy.utilities.base import verbosityManager as vbMng
from rrompy.utilities.exception_manager import RROMPyWarning
from rrompy.parameter import parameterMap as pMap
__all__ = ['HelmholtzProblemEngine', 'ScatteringProblemEngine']
class HelmholtzProblemEngine(LaplaceBaseProblemEngine):
"""
Solver for generic Helmholtz problems with parametric wavenumber.
- \nabla \cdot (a \nabla u) - omega^2 * n**2 * u = f in \Omega
u = u0 on \Gamma_D
\partial_nu = g1 on \Gamma_N
\partial_nu + h u = g2 on \Gamma_R
Attributes:
verbosity: Verbosity level.
BCManager: Boundary condition manager.
V: Real FE space.
u: Generic trial functions for variational form evaluation.
v: Generic test functions for variational form evaluation.
As: Scipy sparse array representation (in CSC format) of As.
bs: Numpy array representation of bs.
cs: Numpy array representation of cs.
energyNormMatrix: Scipy sparse matrix representing inner product over
V.
energyNormDualMatrix: Scipy sparse matrix representing dual inner
product between Riesz representers V-V.
degree_threshold: Threshold for ufl expression interpolation degree.
omega: Value of omega.
diffusivity: Value of a.
refractionIndex: Value of n.
forcingTerm: Value of f.
DirichletDatum: Value of u0.
NeumannDatum: Value of g1.
RobinDatumG: Value of g2.
RobinDatumH: Value of h.
DirichletBoundary: Function handle to \Gamma_D.
NeumannBoundary: Function handle to \Gamma_N.
RobinBoundary: Function handle to \Gamma_R.
ds: Boundary measure 2-tuple (resp. for Neumann and Robin boundaries).
dsToBeSet: Whether ds needs to be set.
"""
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self._affinePoly = True
self.nAs = 2
self.parameterMap = pMap([2.] + [1.] * (self.npar - 1))
self.refractionIndex = fenONE
@property
def refractionIndex(self):
"""Value of n."""
return self._refractionIndex
@refractionIndex.setter
def refractionIndex(self, refractionIndex):
self.resetAs()
if not isinstance(refractionIndex, (list, tuple,)):
refractionIndex = [refractionIndex, fenZERO]
self._refractionIndex = refractionIndex
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:
self.autoSetDS()
vbMng(self, "INIT", "Assembling operator term A0.", 20)
DirichletBC0 = fen.DirichletBC(self.V, fenZERO,
self.DirichletBoundary)
aRe, aIm = self.diffusivity
hRe, hIm = self.RobinDatumH
termNames = ["diffusivity", "RobinDatumH"]
parsRe = self.iterReduceQuadratureDegree(zip(
[aRe, hRe],
[x + "Real" for x in termNames]))
parsIm = self.iterReduceQuadratureDegree(zip(
[aIm, hIm],
[x + "Imag" for x in termNames]))
a0Re = (aRe * fen.dot(fen.grad(self.u), fen.grad(self.v)) * fen.dx
+ hRe * fen.dot(self.u, self.v) * self.ds(1))
a0Im = (aIm * fen.dot(fen.grad(self.u), fen.grad(self.v)) * fen.dx
+ hIm * fen.dot(self.u, self.v) * self.ds(1))
self.As[0] = (fenics2Sparse(a0Re, parsRe, DirichletBC0, 1)
+ 1.j * fenics2Sparse(a0Im, parsIm, DirichletBC0, 0))
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)
class ScatteringProblemEngine(HelmholtzProblemEngine):
"""
Solver for scattering problems with parametric wavenumber.
- \nabla \cdot (a \nabla u) - omega^2 * n**2 * u = f in \Omega
u = u0 on \Gamma_D
\partial_nu = g1 on \Gamma_N
\partial_nu +- i omega u = g2 on \Gamma_R
Attributes:
verbosity: Verbosity level.
BCManager: Boundary condition manager.
V: Real FE space.
u: Generic trial functions for variational form evaluation.
v: Generic test functions for variational form evaluation.
As: Scipy sparse array representation (in CSC format) of As.
bs: Numpy array representation of bs.
cs: Numpy array representation of cs.
energyNormMatrix: Scipy sparse matrix representing inner product over
V.
energyNormDualMatrix: Scipy sparse matrix representing dual inner
product between Riesz representers V-V.
degree_threshold: Threshold for ufl expression interpolation degree.
signR: Sign in ABC.
omega: Value of omega.
diffusivity: Value of a.
forcingTerm: Value of f.
DirichletDatum: Value of u0.
NeumannDatum: Value of g1.
RobinDatumG: Value of g2.
DirichletBoundary: Function handle to \Gamma_D.
NeumannBoundary: Function handle to \Gamma_N.
RobinBoundary: Function handle to \Gamma_R.
ds: Boundary measure 2-tuple (resp. for Neumann and Robin boundaries).
dsToBeSet: Whether ds needs to be set.
"""
def __init__(self, *args, **kwargs):
self.silenceWarnings = True
super().__init__(*args, **kwargs)
self._affinePoly = True
del self.silenceWarnings
self.nAs = 3
self.parameterMap = pMap(1., self.npar)
self.signR = - 1.
@property
def RobinDatumH(self):
"""Value of h."""
if not hasattr(self, "silenceWarnings"):
RROMPyWarning("Scattering problems do not allow changes of h.")
return self.signR
@RobinDatumH.setter
def RobinDatumH(self, RobinDatumH):
if not hasattr(self, "silenceWarnings"):
RROMPyWarning(("Scattering problems do not allow changes of h. "
"Ignoring assignment."))
return
@property
def signR(self):
"""Value of signR."""
return self._signR
@signR.setter
def signR(self, signR):
self.resetAs()
self._signR = signR
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)
aRe, aIm = self.diffusivity
parsRe = self.iterReduceQuadratureDegree(zip([aRe],
["diffusivityReal"]))
parsIm = self.iterReduceQuadratureDegree(zip([aIm],
["diffusivityImag"]))
a0Re = aRe * fen.dot(fen.grad(self.u), fen.grad(self.v)) * fen.dx
a0Im = aIm * fen.dot(fen.grad(self.u), fen.grad(self.v)) * fen.dx
self.As[0] = (fenics2Sparse(a0Re, parsRe, DirichletBC0, 1)
+ 1.j * fenics2Sparse(a0Im, parsIm, DirichletBC0, 0))
vbMng(self, "DEL", "Done assembling operator term.", 20)
if self.As[1] is None:
self.autoSetDS()
vbMng(self, "INIT", "Assembling operator term A1.", 20)
DirichletBC0 = fen.DirichletBC(self.V, fenZERO,
self.DirichletBoundary)
a1 = fen.dot(self.u, self.v) * self.ds(1)
self.As[1] = (self.signR * 1.j
* fenics2Sparse(a1, {}, 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)
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"]))
a2Re = - n2Re * fen.dot(self.u, self.v) * fen.dx
a2Im = - n2Im * fen.dot(self.u, self.v) * fen.dx
self.As[2] = (fenics2Sparse(a2Re, parsRe, DirichletBC0, 0)
+ 1.j * fenics2Sparse(a2Im, parsIm, DirichletBC0, 0))
vbMng(self, "DEL", "Done assembling operator term.", 20)

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