def runTest(self):
"""Solve Stokes problem, try splitting and other small things."""
m = MeshTri()
m.refine()
m.define_boundary('centreline',
lambda x: x[0] == .5,
boundaries_only=False)
m.refine(3)
e = ElementVectorH1(ElementTriP2()) * ElementTriP1()
m.define_boundary('up', lambda x: x[1] == 1.)
m.define_boundary('rest', lambda x: x[1] != 1.)
basis = InteriorBasis(m, e)
self.assertEqual(
basis.get_dofs(m.boundaries['centreline']).all().size,
(2 + 1) * (2**(1 + 3) + 1) + 2 * 2**(1 + 3))
self.assertEqual(basis.find_dofs()['centreline'].all().size,
(2 + 1) * (2**(1 + 3) + 1) + 2 * 2**(1 + 3))
@BilinearForm
def bilinf(u, p, v, q, w):
from skfem.helpers import grad, ddot, div
return (ddot(grad(u), grad(v)) - div(u) * q - div(v) * p -
1e-2 * p * q)
S = asm(bilinf, basis)
D = basis.find_dofs(skip=['u^2'])
x = basis.zeros()
x[D['up'].all('u^1^1')] = .1
x = solve(*condense(S, basis.zeros(), x=x, D=D))
(u, u_basis), (p, p_basis) = basis.split(x)
self.assertEqual(len(u), m.p.shape[1] * 2 + m.facets.shape[1] * 2)
self.assertEqual(len(p), m.p.shape[1])
self.assertTrue(np.sum(p - x[basis.nodal_dofs[2]]) < 1e-8)
U, P = basis.interpolate(x)
self.assertTrue(isinstance(U.value, np.ndarray))
self.assertTrue(isinstance(P.value, np.ndarray))
self.assertTrue((basis.doflocs[:, D['up'].all()][1] == 1.).all())
def runTest(self):
m = self.mesh().refined(4)
basis = InteriorBasis(m, self.elem)
boundary_basis = FacetBasis(m, self.elem)
boundary_dofs = boundary_basis.get_dofs().flatten()
def dirichlet(x):
"""return a harmonic function"""
return ((x[0] + 1.j * x[1])**2).real
u = basis.zeros()
A = laplace.assemble(basis)
u[boundary_dofs] = projection(dirichlet,
boundary_basis,
I=boundary_dofs)
u = solve(*enforce(A, x=u, D=boundary_dofs))
@Functional
def gradu(w):
gradu = w['sol'].grad
return dot(gradu, gradu)
self.assertAlmostEqual(
gradu.assemble(basis, sol=basis.interpolate(u)),
8 / 3,
delta=1e-10,
)
def test_dg_element(m, e, edg):
edg = edg(e)
@Functional
def square(w):
return w['random']**2
basis = InteriorBasis(m, e)
basisdg = InteriorBasis(m, edg)
assert_allclose(
square.assemble(basis, random=basis.interpolate(basis.zeros() + 1)),
square.assemble(basisdg,
random=basisdg.interpolate(basisdg.zeros() + 1)),
)
