def assemble(self):
N = self.N
SB = ShenBiharmonicBasis(N, quad=self.quad)
SB.plan((N, N), 0, np.float, {})
x, w = self.x, self.w = SB.points_and_weights(N)
V = SB.vandermonde(x)
# Trial function
P4 = SB.get_vandermonde_basis(V)
# Second derivatives
T2x = SB.get_vandermonde_basis_derivative(V, 2)
# (u'', v)
K = np.zeros((N, N))
K[:-4, :-4] = inner_product((SB, 0), (SB, 2)).diags().toarray()
# ((1-x**2)u, v)
xx = np.broadcast_to((1 - x**2)[:, np.newaxis], (N, N))
#K1 = np.dot(w*P4.T, xx*P4) # Alternative: K1 = np.dot(w*P4.T, ((1-x**2)*P4.T).T)
K1 = np.zeros((N, N))
K1 = SB.scalar_product(xx * P4, K1)
K1 = extract_diagonal_matrix(
K1).diags().toarray() # For improved roundoff
# ((1-x**2)u'', v)
K2 = np.zeros((N, N))
K2 = SB.scalar_product(xx * T2x, K2)
K2 = extract_diagonal_matrix(
K2).diags().toarray() # For improved roundoff
# (u'''', v)
Q = np.zeros((self.N, self.N))
Q[:-4, :-4] = inner_product((SB, 0), (SB, 4)).diags().toarray()
# (u, v)
M = np.zeros((self.N, self.N))
M[:-4, :-4] = inner_product((SB, 0), (SB, 0)).diags().toarray()
Re = self.Re
a = self.alfa
B = -Re * a * 1j * (K - a**2 * M)
A = Q - 2 * a**2 * K + a**4 * M - 2 * a * Re * 1j * M - 1j * a * Re * (
K2 - a**2 * K1)
return A, B
def get_context():
"""Set up context for solver"""
# Get points and weights for Chebyshev weighted integrals
ST = ShenDirichletBasis(params.N[0], quad=params.Dquad)
SB = ShenBiharmonicBasis(params.N[0], quad=params.Bquad)
CT = ST.CT # Chebyshev transform
Nu = params.N[0] - 2 # Number of velocity modes in Shen basis
Nb = params.N[0] - 4 # Number of velocity modes in Shen biharmonic basis
u_slice = slice(0, Nu)
v_slice = slice(0, Nb)
FST = SlabShen_R2C(params.N,
params.L,
comm,
threads=params.threads,
communication=params.communication,
planner_effort=params.planner_effort,
dealias_cheb=params.dealias_cheb)
float, complex, mpitype = datatypes("double")
ST.plan(FST.complex_shape(), 0, complex, {
'threads': params.threads,
'planner_effort': params.planner_effort["dct"]
})
SB.plan(FST.complex_shape(), 0, complex, {
'threads': params.threads,
'planner_effort': params.planner_effort["dct"]
})
# Mesh variables
X = FST.get_local_mesh(ST)
x0, x1, x2 = FST.get_mesh_dims(ST)
K = FST.get_local_wavenumbermesh(scaled=True)
K2 = K[1] * K[1] + K[2] * K[2]
K_over_K2 = zeros((2, ) + FST.complex_shape())
for i in range(2):
K_over_K2[i] = K[i + 1] / np.where(K2 == 0, 1, K2)
# Solution variables
U = zeros((3, ) + FST.real_shape(), dtype=float)
U0 = zeros((3, ) + FST.real_shape(), dtype=float)
U_hat = zeros((3, ) + FST.complex_shape(), dtype=complex)
U_hat0 = zeros((3, ) + FST.complex_shape(), dtype=complex)
g = zeros(FST.complex_shape(), dtype=complex)
# primary variable
u = (U_hat, g)
H_hat = zeros((3, ) + FST.complex_shape(), dtype=complex)
H_hat0 = zeros((3, ) + FST.complex_shape(), dtype=complex)
H_hat1 = zeros((3, ) + FST.complex_shape(), dtype=complex)
dU = zeros((3, ) + FST.complex_shape(), dtype=complex)
hv = zeros(FST.complex_shape(), dtype=complex)
hg = zeros(FST.complex_shape(), dtype=complex)
Source = zeros((3, ) + FST.real_shape(), dtype=float)
Sk = zeros((3, ) + FST.complex_shape(), dtype=complex)
work = work_arrays()
nu, dt, N = params.nu, params.dt, params.N
K4 = K2**2
kx = K[0][:, 0, 0]
# Collect all linear algebra solvers
la = config.AttributeDict(
dict(HelmholtzSolverG=Helmholtz(N[0], np.sqrt(K2[0] + 2.0 / nu / dt),
ST),
BiharmonicSolverU=Biharmonic(N[0],
-nu * dt / 2.,
1. + nu * dt * K2[0],
-(K2[0] + nu * dt / 2. * K4[0]),
quad=SB.quad,
solver="cython"),
HelmholtzSolverU0=Helmholtz(N[0], np.sqrt(2. / nu / dt), ST),
TDMASolverD=TDMA(inner_product((ST, 0), (ST, 0)))))
alfa = K2[0] - 2.0 / nu / dt
# Collect all matrices
mat = config.AttributeDict(
dict(
CDD=inner_product((ST, 0), (ST, 1)),
AB=HelmholtzCoeff(N[0], 1.0, -alfa, ST.quad),
AC=BiharmonicCoeff(N[0],
nu * dt / 2., (1. - nu * dt * K2[0]),
-(K2[0] - nu * dt / 2. * K4[0]),
quad=SB.quad),
# Matrices for biharmonic equation
CBD=inner_product((SB, 0), (ST, 1)),
ABB=inner_product((SB, 0), (SB, 2)),
BBB=inner_product((SB, 0), (SB, 0)),
SBB=inner_product((SB, 0), (SB, 4)),
# Matrices for Helmholtz equation
ADD=inner_product((ST, 0), (ST, 2)),
BDD=inner_product((ST, 0), (ST, 0)),
BBD=inner_product((SB, 0), (ST, 0)),
CDB=inner_product((ST, 0), (SB, 1))))
hdf5file = KMMWriter({
"U": U[0],
"V": U[1],
"W": U[2]
},
chkpoint={
'current': {
'U': U
},
'previous': {
'U': U0
}
},
filename=params.solver + ".h5",
mesh={
"x": x0,
"y": x1,
"z": x2
})
return config.AttributeDict(locals())