Hello,
I am new to Fenics and gmsh and was trying to understand BC implementation. I am trying to produce a volcanic shaped mesh from convection diffusion equation using gmsh+fenics.
I was able to create a similar shape from Poisson's equation but I keep getting error in this one about the 'b' vector [20, 0]. The problem is noted below:
The following is my code:
Dolfin_bcs_example
from dolfin import *
Create mesh and define function space
mesh = Mesh("abhi1.xml")
boundaries = MeshFunction("size_t", mesh, "abhi1_facet_region.xml")
V = FunctionSpace(mesh, "CG", 1)
Define variational problem
u = TrialFunction(V)
v = TestFunction(V)
f = Constant(1.0)
g = Constant(2.0)
b = [20, 0]
a = dot(b, nabla_grad(u))vdx+dot(nabla_grad(u), nabla_grad(v))dx+guvds
L = fvdx+gvds
Define boundary condition values
u1 = Constant(400.0)
u2 = Constant(0.0)
u3 = Constant(0.0)
Define boundary conditions
bc1 = DirichletBC(V, u1, boundaries, 0) - last argument must match with number (or label) of Physical Surface(0)
bc1 = DirichletBC(V, u1, boundaries, 14) #Physical Lines (Hole in the plate)
bc2 = DirichletBC(V, u2, boundaries, 13) #Physical Lines (Outer boundary of the plate)
bc3 = DirichletBC(V, u3, boundaries, 12) #Physical SUrface
Compute solution
u = Function(V)
solve(a == L, u, [bc1, bc2, bc3])
Write solution to file
File("u.pvd") << u
Plot solution
plot(u, interactive=True)
This is the error displayed:
Invalid type conversion: can not be converted to any UFL type.
The representation of the object is:
[20, 0]
Traceback (most recent call last):
File "abhi2.py", line 14, in
a = dot(b, nabla_grad(u))vdx+dot(nabla_grad(u), nabla_grad(v))dx
File "/usr/lib/python2.7/dist-packages/ufl/operators.py", line 142, in dot
a = as_ufl(a)
File "/usr/lib/python2.7/dist-packages/ufl/constantvalue.py", line 406, in as_ufl
"The representation of the object is:\n%r") % (type(expression), expression))
File "/usr/lib/python2.7/dist-packages/ufl/log.py", line 151, in error
raise self._exception_type(self._format_raw(message))
ufl.log.UFLException: Invalid type conversion: can not be converted to any UFL type.
The representation of the object is:
[20, 0]
