def prepare_ho_node(mesh):
import mfem.ser as mfem
nfec = mfem.H1_FECollection(2,
mesh.Dimension())
# mfem.BasisType.ClosedUniform)
nfes = mfem.FiniteElementSpace(mesh,
nfec,
mesh.SpaceDimension(),
mfem.Ordering.byVDIM)
mesh.SetNodalFESpace(nfes)
mesh._linked_obj = (nfes, nfec)
def run_test():
mesh = mfem.Mesh(10, 10, "TRIANGLE")
fec = mfem.H1_FECollection(1, mesh.Dimension())
fespace = mfem.FiniteElementSpace(mesh, fec)
gf = mfem.GridFunction(fespace)
gf.Assign(1.0)
odata = gf.GetDataArray().copy()
visit_dc = mfem.VisItDataCollection("test_gf", mesh)
visit_dc.RegisterField("gf", gf)
visit_dc.Save()
mesh2 = mfem.Mesh("test_gf_000000/mesh.000000")
check_mesh(mesh, mesh2, ".mesh2 does not agree with original")
gf2 = mfem.GridFunction(mesh2, "test_gf_000000/gf.000000")
odata2 = gf2.GetDataArray().copy()
check(odata, odata2, "odata2 file does not agree with original")
visit_dc = mfem.VisItDataCollection("test_gf_gz", mesh)
visit_dc.SetCompression(True)
visit_dc.RegisterField("gf", gf)
visit_dc.Save()
with gzip.open("test_gf_gz_000000/mesh.000000", 'rt') as f:
sio = io.StringIO(f.read())
mesh3 = mfem.Mesh(sio)
check_mesh(mesh, mesh3, ".mesh3 does not agree with original")
with gzip.open("test_gf_gz_000000/gf.000000", 'rt') as f:
sio = io.StringIO(f.read())
# This is where the error is:
gf3 = mfem.GridFunction(mesh3, sio)
odata3 = gf3.GetDataArray()
check(odata, odata3, "gf3 file does not agree with original")
mesh4 = mfem.Mesh("test_gf_gz_000000/mesh.000000")
check_mesh(mesh, mesh4, ".mesh4 does not agree with original")
gf4 = mfem.GridFunction(mesh3, "test_gf_gz_000000/gf.000000")
odata4 = gf4.GetDataArray()
check(odata, odata4, "gf3 file does not agree with original")
print("PASSED")
import mfem.ser as mfem
import io
mesh = mfem.Mesh(3)
fec = mfem.H1_FECollection(1)
fes = mfem.FiniteElementSpace(mesh, fec)
x = mfem.GridFunction(fes)
x.Assign(0.0)
o = io.StringIO()
l1 = mesh.WriteToStream(o)
l2 = x.WriteToStream(o)
v = mfem.Vector([1, 2, 3])
l3 = v.WriteToStream(o)
print("result length: ", l1, " ", l2)
print('result: ', o.getvalue())
# 3. Refine the mesh to increase the resolution. In this example we do
# 'ref_levels' of uniform refinement. We choose 'ref_levels' to be the
# largest number that gives a final mesh with no more than 50,000
# elements.
ref_levels = int(np.floor(np.log(50000. / mesh.GetNE()) / np.log(2.) / dim))
for x in range(ref_levels):
mesh.UniformRefinement()
#5. Define a finite element space on the mesh. Here we use vector finite
# elements, i.e. dim copies of a scalar finite element space. The vector
# dimension is specified by the last argument of the FiniteElementSpace
# constructor. For NURBS meshes, we use the (degree elevated) NURBS space
# associated with the mesh nodes.
if order > 0:
fec = mfem.H1_FECollection(order, dim)
elif mesh.GetNodes():
fec = mesh.GetNodes().OwnFEC()
prinr("Using isoparametric FEs: " + str(fec.Name()))
else:
order = 1
fec = mfem.H1_FECollection(order, dim)
fespace = mfem.FiniteElementSpace(mesh, fec)
print('Number of finite element unknowns: ' + str(fespace.GetTrueVSize()))
# 5. Determine the list of true (i.e. conforming) essential boundary dofs.
# In this example, the boundary conditions are defined by marking all
# the boundary attributes from the mesh as essential (Dirichlet) and
# converting them to a list of true dofs.
ess_tdof_list = mfem.intArray()
if mesh.bdr_attributes.Size() > 0:
ess_bdr = mfem.intArray([1] * mesh.bdr_attributes.Max())
def run(order=1,
static_cond=False,
meshfile=def_meshfile,
visualization=False):
mesh = mfem.Mesh(meshfile, 1, 1)
dim = mesh.Dimension()
# 3. Refine the mesh to increase the resolution. In this example we do
# 'ref_levels' of uniform refinement. We choose 'ref_levels' to be the
# largest number that gives a final mesh with no more than 50,000
# elements.
ref_levels = int(np.floor(
np.log(50000. / mesh.GetNE()) / np.log(2.) / dim))
for x in range(ref_levels):
mesh.UniformRefinement()
#5. Define a finite element space on the mesh. Here we use vector finite
# elements, i.e. dim copies of a scalar finite element space. The vector
# dimension is specified by the last argument of the FiniteElementSpace
# constructor. For NURBS meshes, we use the (degree elevated) NURBS space
# associated with the mesh nodes.
if order > 0:
fec = mfem.H1_FECollection(order, dim)
elif mesh.GetNodes():
fec = mesh.GetNodes().OwnFEC()
prinr("Using isoparametric FEs: " + str(fec.Name()))
else:
order = 1
fec = mfem.H1_FECollection(order, dim)
fespace = mfem.FiniteElementSpace(mesh, fec)
print('Number of finite element unknowns: ' + str(fespace.GetTrueVSize()))
# 5. Determine the list of true (i.e. conforming) essential boundary dofs.
# In this example, the boundary conditions are defined by marking all
# the boundary attributes from the mesh as essential (Dirichlet) and
# converting them to a list of true dofs.
ess_tdof_list = mfem.intArray()
if mesh.bdr_attributes.Size() > 0:
ess_bdr = mfem.intArray([1] * mesh.bdr_attributes.Max())
ess_bdr = mfem.intArray(mesh.bdr_attributes.Max())
ess_bdr.Assign(1)
fespace.GetEssentialTrueDofs(ess_bdr, ess_tdof_list)
#6. Set up the linear form b(.) which corresponds to the right-hand side of
# the FEM linear system, which in this case is (1,phi_i) where phi_i are
# the basis functions in the finite element fespace.
b = mfem.LinearForm(fespace)
one = mfem.ConstantCoefficient(1.0)
b.AddDomainIntegrator(mfem.DomainLFIntegrator(one))
b.Assemble()
#7. Define the solution vector x as a finite element grid function
# corresponding to fespace. Initialize x with initial guess of zero,
# which satisfies the boundary conditions.
x = mfem.GridFunction(fespace)
x.Assign(0.0)
#8. Set up the bilinear form a(.,.) on the finite element space
# corresponding to the Laplacian operator -Delta, by adding the Diffusion
# domain integrator.
a = mfem.BilinearForm(fespace)
a.AddDomainIntegrator(mfem.DiffusionIntegrator(one))
#9. Assemble the bilinear form and the corresponding linear system,
# applying any necessary transformations such as: eliminating boundary
# conditions, applying conforming constraints for non-conforming AMR,
# static condensation, etc.
if static_cond: a.EnableStaticCondensation()
a.Assemble()
A = mfem.OperatorPtr()
B = mfem.Vector()
X = mfem.Vector()
a.FormLinearSystem(ess_tdof_list, x, b, A, X, B)
print("Size of linear system: " + str(A.Height()))
# 10. Solve
AA = mfem.OperatorHandle2SparseMatrix(A)
M = mfem.GSSmoother(AA)
mfem.PCG(AA, M, B, X, 1, 200, 1e-12, 0.0)
# 11. Recover the solution as a finite element grid function.
a.RecoverFEMSolution(X, b, x)
# 12. Save the refined mesh and the solution. This output can be viewed later
# using GLVis: "glvis -m refined.mesh -g sol.gf".
mesh.Print('refined.mesh', 8)
x.Save('sol.gf', 8)
#13. Send the solution by socket to a GLVis server.
if (visualization):
sol_sock = mfem.socketstream("localhost", 19916)
sol_sock.precision(8)
sol_sock.send_solution(mesh, x)
def ex19_main(args):
ref_levels = args.refine
order = args.order
visualization = args.visualization
mu = args.shear_modulus
newton_rel_tol = args.relative_tolerance
newton_abs_tol = args.absolute_tolerance
newton_iter = args.newton_iterations
parser.print_options(args)
meshfile = expanduser(join(path, 'data', args.mesh))
mesh = mfem.Mesh(meshfile, 1, 1)
dim = mesh.Dimension()
for lev in range(ref_levels):
mesh.UniformRefinement()
# 4. Define the shear modulus for the incompressible Neo-Hookean material
c_mu = mfem.ConstantCoefficient(mu)
# 5. Define the finite element spaces for displacement and pressure
# (Taylor-Hood elements). By default, the displacement (u/x) is a second
# order vector field, while the pressure (p) is a linear scalar function.
quad_coll = mfem.H1_FECollection(order, dim)
lin_coll = mfem.H1_FECollection(order - 1, dim)
R_space = mfem.FiniteElementSpace(mesh, quad_coll, dim,
mfem.Ordering.byVDIM)
W_space = mfem.FiniteElementSpace(mesh, lin_coll)
spaces = [R_space, W_space]
R_size = R_space.GetVSize()
W_size = W_space.GetVSize()
# 6. Define the Dirichlet conditions (set to boundary attribute 1 and 2)
ess_bdr_u = mfem.intArray(R_space.GetMesh().bdr_attributes.Max())
ess_bdr_p = mfem.intArray(W_space.GetMesh().bdr_attributes.Max())
ess_bdr_u.Assign(0)
ess_bdr_u[0] = 1
ess_bdr_u[1] = 1
ess_bdr_p.Assign(0)
ess_bdr = [ess_bdr_u, ess_bdr_p]
print("***********************************************************")
print("dim(u) = " + str(R_size))
print("dim(p) = " + str(W_size))
print("dim(u+p) = " + str(R_size + W_size))
print("***********************************************************")
block_offsets = intArray([0, R_size, W_size])
block_offsets.PartialSum()
xp = mfem.BlockVector(block_offsets)
# 9. Define grid functions for the current configuration, reference
# configuration, final deformation, and pressure
x_gf = mfem.GridFunction(R_space)
x_ref = mfem.GridFunction(R_space)
x_def = mfem.GridFunction(R_space)
p_gf = mfem.GridFunction(W_space)
x_gf.MakeRef(R_space, xp.GetBlock(0), 0)
p_gf.MakeRef(W_space, xp.GetBlock(1), 0)
deform = InitialDeformation(dim)
refconfig = ReferenceConfiguration(dim)
x_gf.ProjectCoefficient(deform)
x_ref.ProjectCoefficient(refconfig)
p_gf.Assign(0.0)
# 10. Initialize the incompressible neo-Hookean operator
oper = RubberOperator(spaces, ess_bdr, block_offsets, newton_rel_tol,
newton_abs_tol, newton_iter, mu)
# 11. Solve the Newton system
oper.Solve(xp)
# 12. Compute the final deformation
mfem.subtract_vector(x_gf, x_ref, x_def)
# 13. Visualize the results if requested
if (visualization):
vis_u = mfem.socketstream("localhost", 19916)
visualize(vis_u, mesh, x_gf, x_def, "Deformation", True)
vis_p = mfem.socketstream("localhost", 19916)
visualize(vis_p, mesh, x_gf, p_gf, "Deformation", True)
# 14. Save the displaced mesh, the final deformation, and the pressure
nodes = x_gf
owns_nodes = 0
nodes, owns_nodes = mesh.SwapNodes(nodes, owns_nodes)
mesh.Print('deformed.mesh', 8)
p_gf.Save('pressure.sol', 8)
x_def.Save("deformation.sol", 8)
import numpy as np
class sigma(mfem.MatrixPyCoefficient):
def __init__(self, dim):
mfem.MatrixPyCoefficient.__init__(self, dim)
def EvalValue(self, x):
return np.array([[0.1, 0.], [0., 10.]])
# create sample mesh for square shape
mesh = mfem.Mesh(10, 10, "TRIANGLE")
# create finite element function space
fec = mfem.H1_FECollection(1, mesh.Dimension()) # H1 order=1
fespace = mfem.FiniteElementSpace(mesh, fec)
#
ess_tdof_list = mfem.intArray()
ess_bdr = mfem.intArray([1] * mesh.bdr_attributes.Size())
fespace.GetEssentialTrueDofs(ess_bdr, ess_tdof_list)
# constant coefficient
one = mfem.ConstantCoefficient(1.0)
# define Bilinear and Linear operator
a = mfem.BilinearForm(fespace)
a.AddDomainIntegrator(mfem.DiffusionIntegrator(sigma(2)))
a.Assemble()
b = mfem.LinearForm(fespace)
elif ode_solver_type == 13: ode_solver = mfem.RK3SSPSolver()
elif ode_solver_type == 14: ode_solver = mfem.RK4Solver()
elif ode_solver_type == 22: ode_solver = mfem.ImplicitMidpointSolver()
elif ode_solver_type == 23: ode_solver = mfem.SDIRK23Solver()
elif ode_solver_type == 24: ode_solver = mfem.SDIRK34Solver()
else:
print("Unknown ODE solver type: " + str(ode_solver_type))
exit
# 4. Refine the mesh to increase the resolution. In this example we do
# 'ref_levels' of uniform refinement, where 'ref_levels' is a
# command-line parameter.
for lev in range(ref_levels):
mesh.UniformRefinement()
# 5. Define the vector finite element space representing the current and the
# initial temperature, u_ref.
fe_coll = mfem.H1_FECollection(order, dim)
fespace = mfem.FiniteElementSpace(mesh, fe_coll)
fe_size = fespace.GetTrueVSize()
print("Number of temperature unknowns: " + str(fe_size))
u_gf = mfem.GridFunction(fespace)
# 6. Set the initial conditions for u. All boundaries are considered
# natural.
u_0 = InitialTemperature()
u_gf.ProjectCoefficient(u_0)
u = mfem.Vector()
u_gf.GetTrueDofs(u)
# 7. Initialize the conduction operator and the visualization.
oper = ConductionOperator(fespace, alpha, kappa, u)
u_gf.SetFromTrueDofs(u)
# - The interfacial space, xhat_space, contains the interfacial unknowns
# and does not have essential BC.
# - The test space, test_space, is an enriched space where the enrichment
# degree may depend on the spatial dimension of the domain, the type of
# the mesh and the trial space order.
trial_order = order
trace_order = order - 1;
test_order = order # reduced order, full order is (order + dim - 1)
if (dim == 2 and (order%2 == 0 or (mesh.MeshGenerator() & 2 and order > 1))):
test_order = test_order + 1
if (test_order < trial_order):
print("Warning, test space not enriched enough to handle primal trial space")
x0_fec = mfem.H1_FECollection(trial_order, dim)
xhat_fec = mfem.RT_Trace_FECollection(trace_order, dim)
test_fec = mfem.L2_FECollection(test_order, dim)
x0_space = mfem.FiniteElementSpace(mesh, x0_fec)
xhat_space = mfem.FiniteElementSpace(mesh, xhat_fec)
test_space = mfem.FiniteElementSpace(mesh, test_fec)
# 5. Define the block structure of the problem, by creating the offset
# variables. Also allocate two BlockVector objects to store the solution
# and rhs.
x0_var = 0; xhat_var = 1; NVAR = 2
s0 = x0_space.GetVSize()
s1 = xhat_space.GetVSize()
mesh.AddTriangle(tri_e[j], j + 1)
mesh.FinalizeTriMesh(1, 1, True)
else:
quad_v = [[-1, -1, -1], [+1, -1, -1], [+1, +1, -1], [-1, +1, -1],
[-1, -1, +1], [+1, -1, +1], [+1, +1, +1], [-1, +1, +1]]
quad_e = [[3, 2, 1, 0], [0, 1, 5, 4], [1, 2, 6, 5], [2, 3, 7, 6],
[3, 0, 4, 7], [4, 5, 6, 7]]
for j in range(Nvert):
mesh.AddVertex(quad_v[j])
for j in range(Nelem):
mesh.AddQuad(quad_e[j], j + 1)
mesh.FinalizeQuadMesh(1, 1, True)
# Set the space for the high-order mesh nodes.
fec = mfem.H1_FECollection(order, mesh.Dimension())
nodal_fes = mfem.FiniteElementSpace(mesh, fec, mesh.SpaceDimension())
mesh.SetNodalFESpace(nodal_fes)
def SnapNodes(mesh):
nodes = mesh.GetNodes()
node = mfem.Vector(mesh.SpaceDimension())
for i in np.arange(nodes.FESpace().GetNDofs()):
for d in np.arange(mesh.SpaceDimension()):
node[d] = nodes[nodes.FESpace().DofToVDof(i, d)]
node /= node.Norml2()
for d in range(mesh.SpaceDimension()):
nodes[nodes.FESpace().DofToVDof(i, d)] = node[d]
