Source code for pina.problem.zoo.poisson_2d_square
"""Formulation of the Poisson problem in a square domain."""
import torch
from ... import Condition
from ...operator import laplacian
from ...problem import SpatialProblem
from ...domain import CartesianDomain
from ...equation import Equation, FixedValue
def laplace_equation(input_, output_):
"""
Implementation of the laplace equation.
:param LabelTensor input_: Input data of the problem.
:param LabelTensor output_: Output data of the problem.
:return: The residual of the laplace equation.
:rtype: LabelTensor
"""
force_term = (
torch.sin(input_.extract(["x"]) * torch.pi)
* torch.sin(input_.extract(["y"]) * torch.pi)
* (2 * torch.pi**2)
)
delta_u = laplacian(output_, input_, components=["u"], d=["x", "y"])
return delta_u - force_term
[docs]
class Poisson2DSquareProblem(SpatialProblem):
r"""
Implementation of the 2-dimensional Poisson problem in the square domain
:math:`[0, 1] \times [0, 1]`.
:Example:
>>> problem = Poisson2DSquareProblem()
"""
output_variables = ["u"]
spatial_domain = CartesianDomain({"x": [0, 1], "y": [0, 1]})
domains = {
"D": CartesianDomain({"x": [0, 1], "y": [0, 1]}),
"g1": CartesianDomain({"x": [0, 1], "y": 1.0}),
"g2": CartesianDomain({"x": [0, 1], "y": 0.0}),
"g3": CartesianDomain({"x": 1.0, "y": [0, 1]}),
"g4": CartesianDomain({"x": 0.0, "y": [0, 1]}),
}
conditions = {
"g1": Condition(domain="g1", equation=FixedValue(0.0)),
"g2": Condition(domain="g2", equation=FixedValue(0.0)),
"g3": Condition(domain="g3", equation=FixedValue(0.0)),
"g4": Condition(domain="g4", equation=FixedValue(0.0)),
"D": Condition(domain="D", equation=Equation(laplace_equation)),
}
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def solution(self, pts):
"""
Implementation of the analytical solution of the Poisson problem.
:param LabelTensor pts: Points where the solution is evaluated.
:return: The analytical solution of the Poisson problem.
:rtype: LabelTensor
"""
sol = -(
torch.sin(pts.extract(["x"]) * torch.pi)
* torch.sin(pts.extract(["y"]) * torch.pi)
)
sol.labels = self.output_variables
return sol