def run_fokker_planck(nx, num_steps, t_0 = 0, t_final=10):
# define mesh
mesh = IntervalMesh(nx, -200, 200)
# define function space.
V = FunctionSpace(mesh, "Lagrange", 1)
# Homogenous Neumann BCs don't have to be defined as they are the default in dolfin
# define parameters.
dt = (t_final-t_0) / num_steps
# set mu and sigma
mu = Constant(-1)
D = Constant(1)
# define initial conditions u_0
u_0 = Expression('x[0]', degree=1)
# set U_n to be the interpolant of u_0 over the function space V. Note that
# u_n is the value of u at the previous timestep, while u is the current value.
u_n = interpolate(u_0, V)
# Define variational problem
u = TrialFunction(V)
v = TestFunction(V)
F = u*v*dx + dt*inner(D*grad(u), grad(v))*dx + dt*mu*grad(u)[0]*v*dx - inner(u_n, v)*dx
# isolate the bilinear and linear forms.
a, L = lhs(F), rhs(F)
# initialize function to capture solution.
t = 0
u_h = Function(V)
plt.figure(figsize=(15, 15))
# time-stepping section
for n in range(num_steps):
t += dt
# compute solution
solve(a == L, u_h)
u_n.assign(u_h)
# Plot solutions intermittently
if n % (num_steps // 10) == 0 and num_steps > 0:
plot(u_h, label='t = %s' % t)
plt.legend()
plt.grid()
plt.title("Finite Element Solutions to Fokker-Planck Equation with $\mu(x, t) = -(x+1)$ , $D(x, t) = e^t x^2$, $t_n$ = %s" % t_final)
plt.ylabel("$u(x, t)$")
plt.xlabel("x")
plt.savefig("fpe/fokker-planck-solutions-mu.png")
plt.clf()
# return the approximate solution evaluated on the coordinates, and the actual coordinates.
return u_n.compute_vertex_values(), mesh.coordinates()
def plotSol(self, func):
(Asol, Qsol) = self.U0.split()
if func == "A":
fe.plot(Asol)
elif func == "Q":
fe.plot(Qsol)
else:
raise ValueError('input can either be "Q" or "A"')
def impl_dyn(w0, dt=1.e-5, t_end=1.e-4, show_plots=False):
(u0, p0, v0) = fe.split(w0)
bcs_u, bcs_p, bcs_v = load_2d_muscle_bc(V_upv.sub(0), V_upv.sub(1),
V_upv.sub(2), boundaries)
# Lagrange function (without constraint)
(u1, p1, v1) = fe.TrialFunctions(V_upv)
(eta, q, xi) = fe.TestFunctions(V_upv)
F = deformation_grad(u1)
I_1, I_2, J = invariants(F)
F_iso = isochronic_deformation_grad(F, J)
#I_1_iso, I_2_iso = invariants(F_iso)[0:2]
W = material_mooney_rivlin(I_1, I_2, c_10, c_01)
g = incompr_constr(J)
L = -W
P = first_piola_stress(L, F)
G = incompr_stress(g, F)
a_dyn_u = inner(u1 - u0, eta) * dx - dt * inner(v1, eta) * dx
a_dyn_p = inner(g, q) * dx
a_dyn_v = rho * inner(v1 - v0, xi) * dx + dt * (inner(
P, grad(xi)) * dx + inner(p1 * G, grad(xi)) * dx - inner(B, xi) * dx)
a = a_dyn_u + a_dyn_p + a_dyn_v
w1 = fe.Function(V_upv)
sol = []
t = 0
while t < t_end:
print("progress: %f" % (100. * t / t_end))
fe.solve(a == 0, w1, bcs_u + bcs_p + bcs_v)
if fe.norm(w1.vector()) > 1e7:
print('ERROR: norm explosion')
break
# update initial values for next step
w0.assign(w1)
t += dt
if show_plots:
# plot result
fe.plot(w0.sub(0), mode='displacement')
plt.show()
# save solutions
sol.append(Solution(t=t))
sol[-1].upv.assign(w0)
return sol, W, kappa
def drawSolution(self):
plt.figure(figsize=(10, 5))
plt.subplot(1, 2, 1)
imuR = fe.plot(self.uReal, title='Real part of the solution')
plt.colorbar(imuR)
plt.subplot(1, 2, 2)
imuI = fe.plot(self.uImag, title='Imaginary part of the solution')
plt.colorbar(imuI)
plt.show()
def plot_diffusion_coef(self, entries='01'):
indices = [int(entry) for entry in entries]
vector = np.zeros(2)
vector[indices] = 1
print(vector)
fevec = fe.Constant(vector)
val = fe.dot(self.composed_diff_coef, fevec)
val = fe.dot(fevec, val)
fe.plot(val, mesh=self.mesh)
plt.show()
def _solve_cell_problems(self):
# Solves the cell problems (one for each space dimension)
w = fe.TrialFunction(self.function_space)
v = fe.TestFunction(self.function_space)
a = self.a_y * fe.dot(fe.grad(w), fe.grad(v)) * fe.dx
for i in range(self.dim):
L = fe.div(self.a_y * self.e_is[i]) * v * fe.dx
bc = fe.DirichletBC(self.function_space, self.bc_function,
PoissonSolver.boundary)
fe.solve(a == L, self.cell_solutions[i], bc)
fe.plot(self.cell_solutions[i])
def xest_second_tutorial(self):
T = 2.0 # final time
num_steps = 50 # number of time steps
dt = T / num_steps # time step size
# Create mesh and define function space
nx = ny = 30
mesh = fenics.RectangleMesh(fenics.Point(-2, -2), fenics.Point(2, 2),
nx, ny)
V = fenics.FunctionSpace(mesh, 'P', 1)
# Define boundary condition
def boundary(x, on_boundary):
return on_boundary
bc = fenics.DirichletBC(V, fenics.Constant(0), boundary)
# Define initial value
u_0 = fenics.Expression('exp(-a*pow(x[0], 2) - a*pow(x[1], 2))',
degree=2,
a=5)
u_n = fenics.interpolate(u_0, V)
# Define variational problem
u = fenics.TrialFunction(V)
v = fenics.TestFunction(V)
f = fenics.Constant(0)
F = u * v * fenics.dx + dt * fenics.dot(fenics.grad(u), fenics.grad(
v)) * fenics.dx - (u_n + dt * f) * v * fenics.dx
a, L = fenics.lhs(F), fenics.rhs(F)
# Create VTK file for saving solution
vtkfile = fenics.File(
os.path.join(os.path.dirname(__file__), 'output', 'heat_gaussian',
'solution.pvd'))
# Time-stepping
u = fenics.Function(V)
t = 0
not_initialised = True
for n in range(num_steps):
# Update current time
t += dt
# Compute solution
fenics.solve(a == L, u, bc)
# Save to file and plot solution
vtkfile << (u, t)
# Here we'll need to call tripcolor ourselves to get access to the color range
fenics.plot(u)
animation_camera.snap()
u_n.assign(u)
animation = animation_camera.animate()
animation.save(
os.path.join(os.path.dirname(__file__), 'output',
'heat_gaussian.mp4'))
def solve_poisson_with_fem(lightweight=False):
# Create mesh and define function space
mesh = fs.UnitSquareMesh(8, 8)
V = fs.FunctionSpace(mesh, 'P', 1)
# Define boundary condition
u_code = 'x[0] + 2*x[1] + 1'
u_D = fs.Expression(u_code, degree=2)
def boundary(x, on_boundary):
return on_boundary
bc = fs.DirichletBC(V, u_D, boundary)
# Define variational problem
u = fs.Function(V) # Note: not TrialFunction!
v = fs.TestFunction(V)
# f = fs.Expression(f_code, degree=2)
f_code = '-10*x[0] - 20*x[1] - 10'
f = fs.Expression(f_code, degree=2)
F = q(u) * fs.dot(fs.grad(u), fs.grad(v)) * fs.dx - f * v * fs.dx
# Compute solution
fs.solve(F == 0, u, bc)
# Plot solution
fs.plot(u)
# Compute maximum error at vertices. This computation illustrates
# an alternative to using compute_vertex_values as in poisson.py.
u_e = fs.interpolate(u_D, V)
# Restore numpy object
image1d = np.empty((81, ), dtype=np.float)
for v in fs.vertices(mesh):
image1d[v.index()] = u(*mesh.coordinates()[v.index()])
if not lightweight:
error_max = np.abs(u_e.vector().get_local() -
u.vector().get_local()).max()
print('error_max = ', error_max)
fs.plot(u)
plt.show()
save_contour(image1d, 1.0, 1.0, 'poisson')
return image1d
def solve_poisson_eps(h, eps, plot=False):
eps = fe.Constant(eps)
n = int(1 / h)
# Create mesh and define function space
mesh = fe.UnitIntervalMesh(n)
V = fe.FunctionSpace(mesh, 'P', 1)
# Define boundary condition
u_D = fe.Constant(0.0)
# Find exact solution:
u_exact = fe.Expression(
"(1./2 - x[0]) * (2 * x[0] + eps/(2*pi) * sin(2*pi*x[0]/eps)) "
"+ eps*eps/(2*pi*2*pi) * (1 - cos(2*pi*x[0]/eps)) + x[0]*x[0]",
eps=eps,
degree=4)
def boundary(x, on_boundary):
return on_boundary
bc = fe.DirichletBC(V, u_D, boundary)
# Define variational problem
u = fe.TrialFunction(V)
v = fe.TestFunction(V)
f = fe.Constant(1)
A = fe.Expression('1./(2+cos(2*pi*x[0]/eps))', eps=eps, degree=2)
a = A * fe.dot(fe.grad(u), fe.grad(v)) * fe.dx
L = f * v * fe.dx
# Compute solution
u = fe.Function(V)
fe.solve(a == L, u, bc)
if plot:
# Plot solution
fe.plot(u)
fe.plot(u_exact, mesh=mesh)
# Hold plot
fe.interactive()
# # Save solution to file in VTK format
# vtkfile = fe.File('poisson/solution.pvd')
# vtkfile << u
# Compute error
err_norm = fe.errornorm(u_exact, u, 'L2')
return err_norm
def solve_pde(self):
u = fe.Function(self.function_space)
v = fe.TestFunction(self.function_space)
u_old = fe.project(self.u_0, self.function_space)
# Todo: Average right hand side if we choose it non-constant
flux = self.dt * fe.dot(
self.composed_diff_coef *
(fe.grad(u) + self.drift_function(u)), fe.grad(v)) * fe.dx
bilin_part = u * v * fe.dx + flux
funtional_part = self.rhs * v * self.dt * fe.dx + u_old * v * fe.dx
full_form = bilin_part - funtional_part
num_steps = int(self.T / self.dt) + 1
bc = fe.DirichletBC(self.function_space, self.u_boundary,
MembraneSimulator.full_boundary)
for n in range(num_steps):
print("Step %d" % n)
self.time += self.dt
fe.solve(full_form == 0, u, bc)
# fe.plot(u)
# plt.show()
# print(fe.errornorm(u_old, u))
u_old.assign(u)
self.file << (u, self.time)
f = fe.plot(u)
plt.rc('text', usetex=True)
plt.colorbar(f, format='%.0e')
plt.title(r'Macroscopic density profile of $u(x,t)$ at $t=1$')
plt.xlabel(r'$x_1$')
plt.ylabel(r'$x_2$')
plt.show()
def fplot(f, compare=None, dim=None, xmin=0, xmax=1, npoints=100,
axes=None, legend=None, mesh=None):
"""plot a function f
Positional parameter:
f: the function to be plotted
Keyword parameters:
dim=1: dimensionality of the argument of f
npoints=100: number points to plot
xmin=0, xmax=1: range to plot
"""
if not dim:
if mesh:
dim = mesh.geometry().dim()
else:
dim = 1
if (dim > 1):
#
# compare ignored in this case
#
p = fe.plot(f, mesh=mesh, axes=axes)
plt.colorbar(p)
return p
if not axes:
axes = plt.gca()
xs = np.linspace(xmin, xmax, npoints)
if compare:
p = axes.plot(xs, [f(x) for x in xs], 'b',
xs, [compare(x) for x in xs], 'r')
if legend:
plt.legend(p, legend)
else:
p = axes.plot(xs, [f(x) for x in xs], 'b')
return p
def test_video_loading():
m = UnitSquareMesh(30, 30)
V = FunctionSpace(m, "CG", 4)
video = VideoData(element=V.ufl_element())
video.load_video("video_data/ach12.mp4")
print(video)
plot(video, mesh=m)
plt.show()
video.set_time(10000.)
plot(video, mesh=m)
plt.show()
assert True
def run(self):
domain = self._create_domain()
mesh = generate_mesh(domain, MESH_PTS)
# fe.plot(mesh)
# plt.show()
self._create_boundary_expression()
Omega = fe.FunctionSpace(mesh, 'CG', 2)
sigma = self.conductivity
Theta = fe.Function(Omega)
v = fe.TestFunction(Omega)
LHS = sigma * fe.inner(fe.grad(Theta), fe.grad(v)) * fe.dx - self.boundary_exp * v * fe.ds
fe.solve(LHS == 0, Theta, solver_parameters={"newton_solver": {"absolute_tolerance": 1e-4}})
fe.plot(Theta, "solution")
plt.show()
def plot(eigenvalues: np.array, eigenfunctions: List[fenics.Function],
**kwargs) -> None:
"""Plot eigenvalues and eigenfunctions.
Convenience function for plotting the results of the eigenfunction
decomposition.
"""
num_eigenpairs = len(eigenvalues)
assert num_eigenpairs == len(eigenfunctions)
import matplotlib.pyplot as plt
k = int(np.ceil(np.sqrt(num_eigenpairs - 1)))
for i, (ew, ev) in enumerate(zip(eigenvalues[1:], eigenfunctions[1:])):
ax = plt.subplot(k, k, i + 1)
ax.axis('off')
ax.set_title('$\lambda_{{{}}} = {:.2f}$'.format(i + 1, ew))
fenics.plot(ev, **kwargs)
def solve_pde(self, name='pde'):
u = fe.Function(self.function_space)
v = fe.TestFunction(self.function_space)
u_old = fe.project(self.u_0, self.function_space)
# Todo: Average right hand side if we choose it non-constant
flux = self.dt * fe.dot(
self.composed_diff_coef *
(fe.grad(u) + self.drift_function(u)), fe.grad(v)) * fe.dx
bilin_part = u * v * fe.dx + flux
funtional_part = self.rhs * v * self.dt * fe.dx + u_old * v * fe.dx
full_form = bilin_part - funtional_part
num_steps = int(self.T / self.dt) + 1
bc = fe.DirichletBC(self.function_space, self.u_boundary,
MembraneSimulator.full_boundary)
for n in range(num_steps):
print("Step %d" % n)
self.time += self.dt
fe.solve(full_form == 0, u, bc)
fe.plot(u)
plt.savefig('images/plt%d.pdf' % n)
plt.show()
# print(fe.errornorm(u_old, u))
u_old.assign(u)
self.file << (u, self.time)
plt.figure()
# u=u+1E-9
f = fe.plot(u)
# f = fe.plot(u,norm=colors.LogNorm(vmin=1E-9,vmax=2E-4))
plt.rc('text', usetex=True)
plt.colorbar(f, format='%.0e')
plt.title(r'Macroscopic density $u(x,t=1)$ for $\alpha=%.1f$' %
MembraneSimulator.alpha)
plt.xlabel(r'$x_1$')
plt.ylabel(r'$x_2$')
plt.savefig('%s.pdf' % name)
plt.show()
def demo_video_complex():
#comm_mpi4py = fe.mpi_comm_world().tompi4py()
#rk = comm_mpi4py.Get_rank()
#if rk == 0:
g = GmshInterface("geo/movie_2.geo", dim=2)
g.generate_xml("geo/movie_2.xml",lc=1.,replace=False)
#comm_mpi4py.Barrier()
d.load_mesh("geo/movie_2.xml")
d.boundary_fnc = lambda x: x[0] > -5. and x[1] < 5.
fe.plot(d.mesh)
plt.show()
d.compute_potential_flow()
fe.plot(d.flow)
plt.show()
d.load_video("video_data/ach12.mp4")
d.compute_conv_diff_reac_video(video_ref=[0,0],video_size=[99.,69.])
def plot(object, **kwargs):
"""
Plot the given object based on its type.
Parameters
----------
object: The object to be plotted.
**kwargs: Same kwargs as the ones defined for fenics.plot().
Check docs to see all available arguments.
Returns
-------
None.
"""
kwargs.setdefault('figsize', (12, 7))
# Check if the given object is a mesh or submesh
plt.figure(figsize=kwargs.get('figsize'))
kwargs.pop('figsize')
pp = fn.plot(object, **kwargs)
plt.colorbar(pp)
plt.show()
def plot_curves(t, soln, opts=defplotopts):
min = soln.meshstats['xmin']
max = soln.meshstats['xmax']
nplots = len(opts['subspaces'])
names = opts['names']
dim = soln.dim
soln.load(t)
width = 4.0 * nplots + 2.0 * (nplots - 1)
fig = plt.figure(1, figsize=(width, 5))
currplot = 1
fig.clf()
params = soln.params(t)
try:
labelval = params[opts['label']]
except KeyError:
labelval = t
label = '%s = %.4g' % (opts['label'], labelval)
for name, subspace in zip(names, opts['subspaces']):
ra = fig.add_subplot(1, nplots, currplot)
if type(subspace) == int:
ssfunc = soln.function.sub(subspace)
elif subspace == 'V':
ssfunc = Vufl(soln, t)
if dim == 1:
p = fplot(ssfunc, xmin=min, xmax=max)
plt.title("%s\n%s" % (name, label))
elif dim == 2:
p = fe.plot(ssfunc, title="%s\n%s" % (name, label))
if opts['colorbar']:
try:
plt.colorbar(p)
except AttributeError:
pass
else:
raise KSDGException("can only plot 1 or 2 dimensions")
dofs = np.array(ssfunc.function_space().dofmap().dofs())
fvec = ssfunc.vector()[:]
ymin, ymax = np.min(fvec[dofs]), np.max(fvec[dofs])
plt.xlabel('(%7g, %7g)' % (ymin, ymax), axes=ra)
currplot += 1
return (fig)
def plot(f):
""" This patches `fenics.plot` which is incorrect for functions on refind 1D meshes.
See https://bitbucket.org/fenics-project/dolfin/issues/1029/plotting-1d-function-incorrectly-ignores
"""
if (type(f) == fenics.Function) and (
f.function_space().mesh().topology().dim() == 1):
mesh = f.function_space().mesh()
C = f.compute_vertex_values(mesh)
X = list(mesh.coordinates()[:, 0])
sorted_C = [c for _, c in sorted(zip(X, C))]
return matplotlib.pyplot.plot(sorted(X), sorted_C)
else:
return fenics.plot(f)
def preprocess(fname):
"""Loads mesh, defines system of equations and prepares system matrix."""
mesh = fe.Mesh(fname + ".xml")
if INPUTS['saving']['mesh']:
fe.File(fname + "_mesh.pvd") << mesh
boundaries = fe.MeshFunction('size_t', mesh, fname + '_facet_region.xml')
if INPUTS['saving']['boundaries']:
fe.File(fname + "_subdomains.pvd") << boundaries
subdomains = fe.MeshFunction('size_t', mesh,
fname + '_physical_region.xml')
if INPUTS['saving']['subdomains']:
fe.File(fname + "_subdomains.pvd") << subdomains
if INPUTS['plotting']['mesh']:
fe.plot(mesh, title='Mesh')
if INPUTS['plotting']['boundaries']:
fe.plot(boundaries, title='Boundaries')
if INPUTS['plotting']['subdomains']:
fe.plot(subdomains, title='Subdomains')
fun_space = fe.FunctionSpace(mesh,
INPUTS['element_type'],
INPUTS['element_degree'],
constrained_domain=PeriodicDomain())
if ARGS['--verbose']:
dofmap = fun_space.dofmap()
print('Number of DOFs:', len(dofmap.dofs()))
field = fe.TrialFunction(fun_space)
test_func = fe.TestFunction(fun_space)
cond = Conductivity(subdomains,
fe.Constant(INPUTS['conductivity']['gas']),
fe.Constant(INPUTS['conductivity']['solid']),
degree=0)
system_matrix = -cond * fe.inner(fe.grad(field),
fe.grad(test_func)) * fe.dx
bctop = fe.Constant(INPUTS['boundary_conditions']['top'])
bcbot = fe.Constant(INPUTS['boundary_conditions']['bottom'])
bcs = [
fe.DirichletBC(fun_space, bctop, boundaries, 1),
fe.DirichletBC(fun_space, bcbot, boundaries, 2)
]
field = fe.Function(fun_space)
return system_matrix, field, bcs, cond
bc = fex.DirichletBC(V, u_D, boundary)
# Define variational problem
u = fex.TrialFunction(V)
v = fex.TestFunction(V)
f = fex.Constant(-6.0)
a = fex.dot(fex.grad(u), fex.grad(v)) * fex.dx
L = f * v * fex.dx
# Compute solution
u = fex.Function(V)
fex.solve(a == L, u, bc)
print(u)
# Plot solution and mesh
plt.subplot(2, 1, 1)
fex.plot(u)
#define the boundary conditions
plt.subplot(2, 1, 2)
fex.plot(mesh)
plt.savefig('possion_fex2.png')
#define the boundary conditions
# Save solution to file in VTK format
vtkfile = fex.File('poisson/solution.pvd')
vtkfile << u
# Compute error in L2 norm
error_L2 = fex.errornorm(u_D, u, 'L2')
# Compute maximum error at vertices
vertex_values_u_D = u_D.compute_vertex_values(mesh)
vertex_values_u = u.compute_vertex_values(mesh)
def plot_mesh(self):
FEN.plot(self._mesh)
def plot_u(self):
FEN.plot(self._u)
hessp=SR1(),
tol=1e-7,
constraints=volume_constraint,
bounds=((0, 1.0),) * A.dim(),
options={"verbose": 3, "gtol": 1e-7, "maxiter": 20},
)
q.assign(0.1)
res = minimize(
min_f,
res.x,
method="trust-constr",
jac=True,
hessp=SR1(),
tol=1e-7,
constraints=volume_constraint,
bounds=((0, 1.0),) * A.dim(),
options={"verbose": 3, "gtol": 1e-7, "maxiter": 100},
)
rho_opt_final = from_numpy(res.x, fenics.Function(A))
c = fenics.plot(rho_opt_final)
plt.colorbar(c)
plt.show()
rho_opt_file = fenics.XDMFFile(
fenics.MPI.comm_world, "output/control_solution_final.xdmf"
)
rho_opt_file.write(rho_opt_final)
constraints = [{
"type": "ineq",
"fun": volume_inequality_fun,
"jac": lambda x: jax.grad(volume_inequality_fun)(x),
}]
x0 = np.ones(C.dim()) * max_volume / (L * h)
res = minimize_ipopt(
min_f,
x0,
jac=True,
bounds=((0.0, 1.0), ) * C.dim(),
constraints=constraints,
options={
"print_level": 5,
"max_iter": 100
},
)
rho_opt_final = numpy_to_fenics(res.x, fa.Function(C))
c = fn.plot(rho_opt_final)
plt.colorbar(c)
plt.show()
# Save optimal solution for visualizing with ParaView
# with XDMFFile("1_dist_load/control_solution_1.xdmf") as f:
# f.write(rho_opt)
# values[0] = sin(3.0*x[0])*sin(3.0*x[1])*sin(3.0*x[2])
# f0 = F0(name="f0", label="My expression", degree=2)
class F0(UserExpression):
def eval(self, values, x):
values[0] = sin(3.0 * x[0]) * sin(3.0 * x[1]) * sin(3.0 * x[2])
class F1(UserExpression):
def __init__(self, mesh, *arg, **kwargs):
super().__init__(*arg, **kwargs)
self.mesh = mesh
def eval_cell(self, values, x, cell):
c = Cell(self.mesh, cell.index)
values[0] = sin(3.0 * x[0]) * sin(3.0 * x[1]) * sin(3.0 * x[2])
e0 = F0(degree=2)
e1 = F1(mesh, degree=2)
e2 = Expression("sin(3.0*x[0])*sin(3.0*x[1])*sin(3.0*x[2])", degree=2)
u0 = interpolate(e0, V)
u1 = interpolate(e1, V)
u2 = interpolate(e2, V)
fp = fe.interpolate(f0, V)
fe.plot(fp)
plt.show()
def solve_cell_problems(self, method='regularized', plot=False):
"""
Solve the cell problems for the given PDE by changing the geometry to exclude the zone in the middle
:return:
"""
class PeriodicBoundary(fe.SubDomain):
# Left boundary is "target domain" G
def inside(self, x, on_boundary):
par = MembraneSimulator.w / MembraneSimulator.length
tol = 1E-4
return on_boundary and x[1] >= -tol and x[1] <= tol
# Map right boundary (H) to left boundary (G)
def map(self, x, y):
y[1] = x[1] + 2 * self.eta / MembraneSimulator.length
y[0] = x[0]
mesh_size = 50
# Domain
if method == 'circle':
self.obstacle_radius = self.eta / MembraneSimulator.length / 2
box_begin_point = fe.Point(-self.w / MembraneSimulator.length, 0)
box_end_point = fe.Point(self.w / MembraneSimulator.length,
2 * self.eta / MembraneSimulator.length)
box = mshr.Rectangle(box_begin_point, box_end_point)
cell = box - mshr.Circle(
fe.Point(0, self.eta / MembraneSimulator.length),
self.obstacle_radius, mesh_size)
self.cell_mesh = mshr.generate_mesh(cell, mesh_size)
diff_coef = fe.Constant(
((0, 0), (0, self.D[1, 1]))) # limit for regularisation below.
# elif method == 'diff_coef':
# print("Haha this is going to crash. Also it is horrible in accuracy")
# self.cell_mesh = fe.RectangleMesh(fe.Point(-self.w / MembraneSimulator.length, 0),
# fe.Point(self.w / MembraneSimulator.length,
# 2 * self.eta / MembraneSimulator.length), mesh_size, mesh_size)
# diff_coef = fe.Expression(
# (('0', '0'), ('0', 'val * ((x[0] - c_x)*(x[0] - c_x) + (x[1] - c_y)*(x[1] - c_y) > r*r)')),
# val=(4 * self.ref_T * MembraneSimulator.d2 / MembraneSimulator.length ** 2), c_x=0,
# c_y=(self.eta / MembraneSimulator.length),
# r=self.obstacle_radius, degree=2, domain=self.cell_mesh)
elif method == 'regularized':
box_begin_point = fe.Point(-self.w / MembraneSimulator.length, 0)
box_end_point = fe.Point(self.w / MembraneSimulator.length,
2 * self.eta / MembraneSimulator.length)
box = mshr.Rectangle(box_begin_point, box_end_point)
obstacle_begin_point = fe.Point(
-self.w / MembraneSimulator.length * self.obs_length,
self.eta / MembraneSimulator.length * (1 - self.obs_height))
obstacle_end_point = fe.Point(
self.w / MembraneSimulator.length * self.obs_length,
self.eta / MembraneSimulator.length * (1 + self.obs_height))
obstacle = mshr.Rectangle(obstacle_begin_point, obstacle_end_point)
cell = box - obstacle
self.cell_mesh = mshr.generate_mesh(cell, mesh_size)
diff_coef = fe.Constant(((self.obs_ratio * self.D[0, 0], 0),
(0, self.D[1, 1]))) # defect matrix.
else:
raise ValueError("%s not a valid method to solve cell problem" %
method)
self.cell_fs = fe.FunctionSpace(self.cell_mesh, 'P', 2)
self.cell_solutions = [
fe.Function(self.cell_fs),
fe.Function(self.cell_fs)
]
w = fe.TrialFunction(self.cell_fs)
phi = fe.TestFunction(self.cell_fs)
scaled_unit_vectors = [
fe.Constant((1. / np.sqrt(self.obs_ratio), 0.)),
fe.Constant((0., 1.))
]
for i in range(2):
weak_form = fe.dot(
diff_coef *
(fe.grad(w) + scaled_unit_vectors[i]), fe.grad(phi)) * fe.dx
print("Solving cell problem")
bc = fe.DirichletBC(self.cell_fs, fe.Constant(0),
MembraneSimulator.cell_boundary)
if i == 0:
# Periodicity is applied automatically
bc = None
fe.solve(
fe.lhs(weak_form) == fe.rhs(weak_form), self.cell_solutions[i],
bc)
if plot:
plt.rc('text', usetex=True)
f = fe.plot(self.cell_solutions[i])
plt.colorbar(f)
plt.title(r'Solution to cell problem $w_%d$' % (i + 1))
plt.xlabel(r'$Y_1$')
plt.ylabel(r'$Y_2$')
print("Cell solution")
print(np.min(self.cell_solutions[i].vector().get_local()),
np.max(self.cell_solutions[i].vector().get_local()))
plt.show()
from gmsh_interface import GmshInterface
g = GmshInterface("../geo/simple_muscle_3d.geo")
g.set_parameter("lc",0.1)
g.generate_xml("../geo/test.xml")
from fenics import Mesh, plot
import matplotlib.pyplot as plt
mesh = Mesh("../geo/test.xml")
plot(mesh)
plt.show()
def main():
"""Main function. Organizes workflow."""
fname = str(INPUTS['filename'])
term = Terminal()
print(
term.yellow
+ "Working on file {}.".format(fname)
+ term.normal
)
# Load mesh and physical domains from file.
mesh = fe.Mesh(fname + ".xml")
if INPUTS['saving']['mesh']:
fe.File(fname + "_mesh.pvd") << mesh
if INPUTS['plotting']['mesh']:
fe.plot(mesh, title='Mesh')
subdomains = fe.MeshFunction(
'size_t', mesh, fname + '_physical_region.xml')
if INPUTS['saving']['subdomains']:
fe.File(fname + "_subdomains.pvd") << subdomains
if INPUTS['plotting']['subdomains']:
fe.plot(subdomains, title='Subdomains')
# function space for temperature/concentration
func_space = fe.FunctionSpace(
mesh,
INPUTS['element_type'],
INPUTS['element_degree'],
constrained_domain=PeriodicDomain()
)
# discontinuous function space for visualization
dis_func_space = fe.FunctionSpace(
mesh,
'DG',
INPUTS['element_degree'],
constrained_domain=PeriodicDomain()
)
if ARGS['--verbose']:
print('Number of cells:', mesh.num_cells())
print('Number of faces:', mesh.num_faces())
print('Number of edges:', mesh.num_edges())
print('Number of vertices:', mesh.num_vertices())
print('Number of DOFs:', len(func_space.dofmap().dofs()))
# temperature/concentration field
field = fe.TrialFunction(func_space)
# test function
test_func = fe.TestFunction(func_space)
# function, which is equal to 1 everywhere
unit_function = fe.Function(func_space)
unit_function.assign(fe.Constant(1.0))
# assign material properties to each domain
if INPUTS['mode'] == 'conductivity':
mat_prop = SubdomainConstant(
subdomains,
fe.Constant(INPUTS['conductivity']['gas']),
fe.Constant(INPUTS['conductivity']['solid']),
degree=0
)
elif INPUTS['mode'] == 'diffusivity':
mat_prop = SubdomainConstant(
subdomains,
fe.Constant(INPUTS['diffusivity']['gas']),
fe.Constant(INPUTS['diffusivity']['solid']) *
fe.Constant(INPUTS['solubility'] *
gas_constant * INPUTS['temperature']),
degree=0
)
# assign 1 to gas domain, and 0 to solid domain
gas_content = SubdomainConstant(
subdomains,
fe.Constant(1.0),
fe.Constant(0.0),
degree=0
)
# define structure of foam over whole domain
structure = fe.project(unit_function * gas_content, dis_func_space)
# calculate porosity and wall thickness
porosity = fe.assemble(structure *
fe.dx) / ((XMAX - XMIN) * (YMAX - YMIN) * (ZMAX - ZMIN))
print('Porosity: {0}'.format(porosity))
dwall = wall_thickness(
porosity, INPUTS['morphology']['cell_size'],
INPUTS['morphology']['strut_content'])
print('Wall thickness: {0} m'.format(dwall))
# calculate effective conductivity/diffusivity by analytical model
if INPUTS['mode'] == 'conductivity':
eff_prop = analytical_conductivity(
INPUTS['conductivity']['gas'], INPUTS['conductivity']['solid'],
porosity, INPUTS['morphology']['strut_content'])
print('Analytical model: {0} W/(mK)'.format(eff_prop))
elif INPUTS['mode'] == 'diffusivity':
eff_prop = analytical_diffusivity(
INPUTS['diffusivity']['solid'] *
INPUTS['solubility'], INPUTS['solubility'],
porosity, INPUTS['morphology']['cell_size'], dwall,
INPUTS['temperature'], INPUTS['morphology']['enhancement_par'])
print('Analytical model: {0} m^2/s'.format(eff_prop))
# create system matrix
system_matrix = -mat_prop * \
fe.inner(fe.grad(field), fe.grad(test_func)) * fe.dx
left_side, right_side = fe.lhs(system_matrix), fe.rhs(system_matrix)
# define boundary conditions
bcs = [
fe.DirichletBC(func_space, fe.Constant(
INPUTS['boundary_conditions']['top']), top_bc),
fe.DirichletBC(func_space, fe.Constant(
INPUTS['boundary_conditions']['bottom']), bottom_bc)
]
# compute solution
field = fe.Function(func_space)
fe.solve(left_side == right_side, field, bcs)
# output temperature/concentration at the boundaries
if ARGS['--verbose']:
print('Checking periodicity:')
print('Value at XMIN:', field(XMIN, (YMIN + YMAX) / 3, (ZMIN + ZMAX) / 3))
print('Value at XMAX:', field(XMAX, (YMIN + YMAX) / 3, (ZMIN + ZMAX) / 3))
print('Value at YMIN:', field((XMIN + XMAX) / 3, YMIN, (ZMIN + ZMAX) / 3))
print('Value at YMAX:', field((XMIN + XMAX) / 3, YMAX, (ZMIN + ZMAX) / 3))
print('Value at ZMIN:', field((XMIN + XMAX) / 3, (YMIN + YMAX) / 3, ZMIN))
print('Value at ZMAX:', field((XMIN + XMAX) / 3, (YMIN + YMAX) / 3, ZMAX))
# calculate flux, and effective properties
vec_func_space = fe.VectorFunctionSpace(
mesh,
INPUTS['element_type'],
INPUTS['element_degree']
)
flux = fe.project(-mat_prop * fe.grad(field), vec_func_space)
divergence = fe.project(-fe.div(mat_prop * fe.grad(field)), func_space)
flux_x, flux_y, flux_z = flux.split()
av_flux = fe.assemble(flux_z * fe.dx) / ((XMAX - XMIN) * (YMAX - YMIN))
eff_prop = av_flux * (ZMAX - ZMIN) / (
INPUTS['boundary_conditions']['top']
- INPUTS['boundary_conditions']['bottom']
)
if INPUTS['mode'] == 'conductivity':
print('Numerical model: {0} W/(mK)'.format(eff_prop))
elif INPUTS['mode'] == 'diffusivity':
print('Numerical model: {0} m^2/s'.format(eff_prop))
# projection of concentration has to be in discontinuous function space
if INPUTS['mode'] == 'diffusivity':
sol_field = SubdomainConstant(
subdomains,
fe.Constant(1.0),
fe.Constant(INPUTS['solubility'] *
gas_constant * INPUTS['temperature']),
degree=0
)
field = fe.project(field * sol_field, dis_func_space)
# save results
with open(fname + "_eff_prop.csv", 'w') as textfile:
textfile.write('eff_prop\n')
textfile.write('{0}\n'.format(eff_prop))
fe.File(fname + "_solution.pvd") << field
fe.File(fname + "_structure.pvd") << structure
if INPUTS['saving']['flux']:
fe.File(fname + "_flux.pvd") << flux
if INPUTS['saving']['flux_divergence']:
fe.File(fname + "_flux_divergence.pvd") << divergence
if INPUTS['saving']['flux_components']:
fe.File(fname + "_flux_x.pvd") << flux_x
fe.File(fname + "_flux_y.pvd") << flux_y
fe.File(fname + "_flux_z.pvd") << flux_z
# plot results
if INPUTS['plotting']['solution']:
fe.plot(field, title="Solution")
if INPUTS['plotting']['flux']:
fe.plot(flux, title="Flux")
if INPUTS['plotting']['flux_divergence']:
fe.plot(divergence, title="Divergence")
if INPUTS['plotting']['flux_components']:
fe.plot(flux_x, title='x-component of flux (-kappa*grad(u))')
fe.plot(flux_y, title='y-component of flux (-kappa*grad(u))')
fe.plot(flux_z, title='z-component of flux (-kappa*grad(u))')
if True in INPUTS['plotting'].values():
fe.interactive()
print(
term.yellow
+ "End."
+ term.normal
)
def plot(self):
# Quickplot of the solution
fe.plot(self.diff_coef, mesh=self.mesh)
fe.plot(self.solution)
fe.interactive()
# Update current time
t += dt
# Step 1: Tentative velocity step
b1 = fs.assemble(L1)
[bc.apply(b1) for bc in bcu]
fs.solve(A1, u_.vector(), b1)
# Step 2: Pressure correction step
b2 = fs.assemble(L2)
[bc.apply(b2) for bc in bcp]
fs.solve(A2, p_.vector(), b2)
# Step 3: Velocity correction step
b3 = fs.assemble(L3)
fs.solve(A3, u_.vector(), b3)
# Plot solutions
fs.plot(u_)
plt.pause(0.1)
# Compute error
u_e = fs.Expression(('4*x[1]*(1.0 - x[1])', '0'), degree=2)
u_e = fs.interpolate(u_e, V)
error = np.abs(u_e.vector() - u_.vector()).max()
print('t = %.2f: error = %.3g' % (t, error))
print('max u:', u_.vector().max())
# Update previous solution
u_n.assign(u_)
p_n.assign(p_)