What i can add a time-depend problem to my program ?

Question

I'm a young user a FEniCS Project and I need help. This is my program who calculating a electromagnetic field in biological tissues and I need to add to them a time to see how the field strength varies with difriend time.
Please help my, My study graduaded depends on it. I don't have a time.
Ps. I'm very sorry for my English. I use FEniCS 1.3.0 on Ubuntu
Regards
Paul

 from dolfin import *

    if not has_cgal():
        print "DOLFIN must be compiled with CGAL to run this demo."
        exit(0) class Left(SubDomain):
        def inside(self, x, on_boundary):
            return near(x[0], 0.0)

    class Right(SubDomain):
        def inside(self, x, on_boundary):
            return near(x[0], 5.0)

    class Bottom(SubDomain):
        def inside(self, x, on_boundary):
            return near(x[1], 0.0)

    class Top(SubDomain):
        def inside(self, x, on_boundary):
            return near(x[1], 5.0)

    class Lewo(SubDomain):
        def inside(self, x, on_boundary):
           return near(x[0], 0.25)

    class Prawo(SubDomain):
        def inside(self, x, on_boundary):
            return near(x[0], 4.75)

    class Dol(SubDomain):
        def inside(self, x, on_boundary):
            return near(x[1], 0.25)

    class Gora(SubDomain):
        def inside(self, x, on_boundary):
            return near(x[1], 4.75)

    class Obstacle(SubDomain):
        def inside(self, x, on_boundary):   return (between(x[1], (1.25, 3.75)) and between(x[0], (1.25, 3.75)))


    # Initialize sub-domain instances 
left = Left()
top = Top() 
right = Right() 
bottom = Bottom() 
lewo = Left() 
gora = Top() 
prawo = Right() 
dol = Bottom() 
obstacle = Obstacle()


    # Define 2D geometry 
domain = Rectangle(0., 0., 5., 5.) 
domain.set_subdomain(1, Rectangle(0.25, 0.25, 4.75, 4.75)) 
domain.set_subdomain(2, Rectangle(1.25, 1.25, 3.75, 3.75))

mesh2d = Mesh(domain, 45) 
mf = MeshFunction("size_t", mesh2d, 2, mesh2d.domains()) 
domains = CellFunction("size_t", mesh2d) 
domains.set_all(0) obstacle.mark(domains, 1)

    # Initialize mesh function for boundary domains 
boundaries = FacetFunction("size_t", mesh2d) 
boundaries.set_all(0) 
left.mark(boundaries, 1) 
top.mark(boundaries, 2) 
right.mark(boundaries, 3) 
bottom.mark(boundaries, 4) 
lewo.mark(boundaries, 5) 
gora.mark(boundaries, 6) 
prawo.mark(boundaries, 7) 
dol.mark(boundaries, 8)

    # Define input data 
a0 = Constant(1.25E-1) 
a1 = Constant(2.86E-1) 
a2 = Constant(9.50E-2)
    #g_L = Expression("- 10*exp(- pow(x[1] - 0.5, 2))")
    #g_R = Constant("1.0") f = Constant(1.0)

    # Define function space and basis functions 
V = FunctionSpace(mesh2d, "CG", 2) 
u = TrialFunction(V) 
v = TestFunction(V)

    # Define Dirichlet boundary conditions at top and bottom boundaries 
bcs = [DirichletBC(V, 0.0, boundaries, 1),
           DirichletBC(V, 0.0, boundaries, 2),
           DirichletBC(V, 0.0, boundaries, 3),
           DirichletBC(V, 0.0, boundaries, 4),
           DirichletBC(V, 0.0, boundaries, 5),
           DirichletBC(V, 0.0, boundaries, 6),
           DirichletBC(V, 0.0, boundaries, 7),
           DirichletBC(V, 0.0, boundaries, 8)   ]

    # Define new measures associated with the interior domains and
    # exterior boundaries 
dx = Measure("dx")[domains] 
ds = Measure("ds")[boundaries]

    # Define variational form 
F = (inner(a0*grad(u), grad(v))*dx(0) + inner(a1*grad(u), grad(v))*dx(1) + inner(a2*grad(u), grad(v))*dx(2) - f*v*dx(1) - f*v*dx(2) - f*v*dx(3) - f*v*dx(4) - f*v*dx(5) - f*v*dx(6)
    - f*v*dx(7) - f*v*dx(8))

    # Separate left and right hand sides of equation 
a, L = lhs(F), rhs(F)

    # Solve problem 
u = Function(V) 
solve(a == L, u, bcs)

    plot(u, title="u")

    plot(mesh2d, "2D mesh")

    #plot(mesh2d, "2D mesh")
    # Convert subdomains to mesh function for plotting file = File("tkanka.pvd") file << u
    #plot(mf, "Subdomains") interactive()

It's not clear what you're asking. Try asking a a focussed questions with a compact code example. — Garth N. Wells, Jan 28, 2014

What i can add a time-depend problem to my program ?

1 Answer