Source code for dolfinx.fem.bcs

# Copyright (C) 2017-2021 Chris N. Richardson, Garth N. Wells and Jørgen S. Dokken
#
# This file is part of DOLFINx (https://www.fenicsproject.org)
#
# SPDX-License-Identifier:    LGPL-3.0-or-later
"""Support for representing Dirichlet boundary conditions that are enforced
via modification of linear systems."""

from __future__ import annotations

import numbers
import typing

import numpy.typing

if typing.TYPE_CHECKING:
    from dolfinx.fem.function import Constant, Function

import numpy as np

import dolfinx
from dolfinx import cpp as _cpp


[docs] def locate_dofs_geometrical( V: typing.Union[dolfinx.fem.FunctionSpace, typing.Iterable[dolfinx.fem.FunctionSpace]], marker: typing.Callable, ) -> np.ndarray: """Locate degrees-of-freedom geometrically using a marker function. Args: V: Function space(s) in which to search for degree-of-freedom indices. marker: A function that takes an array of points ``x`` with shape ``(gdim, num_points)`` and returns an array of booleans of length ``num_points``, evaluating to ``True`` for entities whose degree-of-freedom should be returned. Returns: An array of degree-of-freedom indices (local to the process) for degrees-of-freedom whose coordinate evaluates to True for the marker function. If ``V`` is a list of two function spaces, then a 2-D array of shape (number of dofs, 2) is returned. Returned degree-of-freedom indices are unique and ordered by the first column. """ try: return _cpp.fem.locate_dofs_geometrical(V._cpp_object, marker) # type: ignore except AttributeError: _V = [space._cpp_object for space in V] return _cpp.fem.locate_dofs_geometrical(_V, marker)
[docs] def locate_dofs_topological( V: typing.Union[dolfinx.fem.FunctionSpace, typing.Iterable[dolfinx.fem.FunctionSpace]], entity_dim: int, entities: numpy.typing.NDArray[np.int32], remote: bool = True, ) -> np.ndarray: """Locate degrees-of-freedom belonging to mesh entities topologically. Args: V: Function space(s) in which to search for degree-of-freedom indices. entity_dim: Topological dimension of entities where degrees-of-freedom are located. entities: Indices of mesh entities of dimension ``entity_dim`` where degrees-of-freedom are located. remote: True to return also "remotely located" degree-of-freedom indices. Returns: An array of degree-of-freedom indices (local to the process) for degrees-of-freedom topologically belonging to mesh entities. If ``V`` is a list of two function spaces, then a 2-D array of shape (number of dofs, 2) is returned. Returned degree-of-freedom indices are unique and ordered by the first column. """ _entities = np.asarray(entities, dtype=np.int32) try: return _cpp.fem.locate_dofs_topological(V._cpp_object, entity_dim, _entities, remote) # type: ignore except AttributeError: _V = [space._cpp_object for space in V] return _cpp.fem.locate_dofs_topological(_V, entity_dim, _entities, remote)
[docs] class DirichletBC: _cpp_object: typing.Union[ _cpp.fem.DirichletBC_complex64, _cpp.fem.DirichletBC_complex128, _cpp.fem.DirichletBC_float32, _cpp.fem.DirichletBC_float64, ] def __init__(self, bc): """Representation of Dirichlet boundary condition which is imposed on a linear system. Note: Dirichlet boundary conditions should normally be constructed using :func:`fem.dirichletbc` and not using this class initialiser. This class is combined with different base classes that depend on the scalar type of the boundary condition. Args: value: Lifted boundary values function. dofs: Local indices of degrees of freedom in function space to which boundary condition applies. Expects array of size (number of dofs, 2) if function space of the problem, ``V`` is passed. Otherwise assumes function space of the problem is the same of function space of boundary values function. V: Function space of a problem to which boundary conditions are applied. """ self._cpp_object = bc @property def g(self) -> typing.Union[Function, Constant, np.ndarray]: """The boundary condition value(s)""" return self._cpp_object.value @property def function_space(self) -> dolfinx.fem.FunctionSpace: """The function space on which the boundary condition is defined""" return self._cpp_object.function_space
[docs] def dirichletbc( value: typing.Union[Function, Constant, np.ndarray], dofs: numpy.typing.NDArray[np.int32], V: typing.Optional[dolfinx.fem.FunctionSpace] = None, ) -> DirichletBC: """Create a representation of Dirichlet boundary condition which is imposed on a linear system. Args: value: Lifted boundary values function. It must have a ``dtype`` property. dofs: Local indices of degrees of freedom in function space to which boundary condition applies. Expects array of size (number of dofs, 2) if function space of the problem, ``V``, is passed. Otherwise assumes function space of the problem is the same of function space of boundary values function. V: Function space of a problem to which boundary conditions are applied. Returns: A representation of the boundary condition for modifying linear systems. """ if isinstance(value, numbers.Number): value = np.asarray(value) try: dtype = value.dtype if np.issubdtype(dtype, np.float32): bctype = _cpp.fem.DirichletBC_float32 elif np.issubdtype(dtype, np.float64): bctype = _cpp.fem.DirichletBC_float64 elif np.issubdtype(dtype, np.complex64): bctype = _cpp.fem.DirichletBC_complex64 elif np.issubdtype(dtype, np.complex128): bctype = _cpp.fem.DirichletBC_complex128 else: raise NotImplementedError(f"Type {value.dtype} not supported.") except AttributeError: raise AttributeError("Boundary condition value must have a dtype attribute.") # Unwrap value object, if required if isinstance(value, np.ndarray): _value = value else: try: _value = value._cpp_object # type: ignore except AttributeError: _value = value if V is not None: try: bc = bctype(_value, dofs, V) except TypeError: bc = bctype(_value, dofs, V._cpp_object) else: bc = bctype(_value, dofs) return DirichletBC(bc)
[docs] def bcs_by_block( spaces: typing.Iterable[typing.Union[dolfinx.fem.FunctionSpace, None]], bcs: typing.Iterable[DirichletBC], ) -> list[list[DirichletBC]]: """Arrange Dirichlet boundary conditions by the function space that they constrain. Given a sequence of function spaces ``spaces`` and a sequence of DirichletBC objects ``bcs``, return a list where the ith entry is the list of DirichletBC objects whose space is contained in ``space[i]``. """ def _bc_space(V, bcs): "Return list of bcs that have the same space as V" return [bc for bc in bcs if V.contains(bc.function_space)] return [_bc_space(V, bcs) if V is not None else [] for V in spaces]