Hi,
I had a look at introduction_ex4. I found with a DirichletBoundary
object, the diagonal entries in the matrix for boundary nodes were modified
to 1 or 2. I want to add this method to adaptivity_ex2.
It looks quite easy. I just created a DirichletBoundary object and
attached it to the system. I commented out some code with #if 0 and ran it
with *mpirun -n 1 ./.libs/example-dbg -n_timesteps 25 -n_refinements 0
-output_freq 10 -init_timestep 0*
However, I found the dirichlet_bc object did not take effect. After some
debugging, I found libmesh somehow did not recognize boundary edges and
nodes. I don't know what is wrong.
I attach my modified adaptivity_ex2.C and the diff to see if someone can
help on that.
Thank you!
--Junchao Zhang
diff --git a/examples/adaptivity/adaptivity_ex2/adaptivity_ex2.C
b/examples/adaptivity/adaptivity_ex2/adaptivity_ex2.C
index 741b29fb..06e84767 100644
--- a/examples/adaptivity/adaptivity_ex2/adaptivity_ex2.C
+++ b/examples/adaptivity/adaptivity_ex2/adaptivity_ex2.C
@@ -51,6 +51,8 @@
#include "libmesh/numeric_vector.h"
#include "libmesh/dense_matrix.h"
#include "libmesh/dense_vector.h"
+#include "libmesh/dirichlet_boundaries.h"
+#include "libmesh/analytic_function.h"
#include "libmesh/getpot.h"
@@ -105,7 +107,13 @@ Number exact_value (const Point & p,
return exact_solution(p(0), p(1), parameters.get<Real> ("time"));
}
-
+// Define a wrapper for exact_solution that will be needed below
+void exact_solution_wrapper (DenseVector<Number>& output,
+ const Point& p,
+ const Real t)
+{
+ output(0) = exact_solution(p(0), p(1), t);
+}
// Begin the main program. Note that the first
// statement in the program throws an error if
@@ -196,9 +204,11 @@ int main (int argc, char ** argv)
EquationSystems equation_systems (mesh);
MeshRefinement mesh_refinement (mesh);
+#if 0
// First we process the case where we do not read in the solution
if (!read_solution)
{
+#endif
// Read the mesh from file.
mesh.read ("mesh.xda");
@@ -222,15 +232,42 @@ int main (int argc, char ** argv)
// Adds the variable "u" to "Convection-Diffusion". "u"
// will be approximated using first-order approximation.
- system.add_variable ("u", FIRST);
+ unsigned int u_var = system.add_variable ("u", FIRST);
// Give the system a pointer to the matrix assembly
// and initialization functions.
system.attach_assemble_function (assemble_cd);
system.attach_init_function (init_cd);
+ int dim = 2;
+ std::set<boundary_id_type> boundary_ids;
+ boundary_ids.insert(0);
+ boundary_ids.insert(1);
+ if(dim>=2)
+ {
+ boundary_ids.insert(2);
+ boundary_ids.insert(3);
+ }
+ if(dim==3)
+ {
+ boundary_ids.insert(4);
+ boundary_ids.insert(5);
+ }
+
+ std::vector<unsigned int> variables(1);
+ variables[0] = u_var;
+
+ AnalyticFunction<> exact_solution_object(exact_solution_wrapper);
+
+ DirichletBoundary dirichlet_bc(boundary_ids,
+ variables,
+ &exact_solution_object);
+
+ system.get_dof_map().add_dirichlet_boundary(dirichlet_bc);
+
// Initialize the data structures for the equation system.
equation_systems.init ();
+#if 0
}
// Otherwise we read in the solution and mesh
else
@@ -262,6 +299,7 @@ int main (int argc, char ** argv)
libMesh::out << "Initial H1 norm = " << H1norm << std::endl << std::endl;
}
+#endif
// Prints information about the system to the screen.
equation_systems.print_info();
@@ -296,8 +334,10 @@ int main (int argc, char ** argv)
// derived from them) contain old solutions, to use the
// old_local_solution later we now need to specify the system
// type when we ask for it.
+#if 0
TransientLinearImplicitSystem & system =
equation_systems.get_system<TransientLinearImplicitSystem>("Convection-Diffusion");
+#endif
const Real dt = 0.025;
system.time = init_timestep*dt;
@@ -645,6 +685,7 @@ void assemble_cd (EquationSystems & es,
}
}
+#if 0
// At this point the interior element integration has
// been completed. However, we have not yet addressed
// boundary conditions. For this example we will only
@@ -683,6 +724,7 @@ void assemble_cd (EquationSystems & es,
}
}
}
+#endif
// We have now built the element matrix and RHS vector in terms
------------------------------------------------------------------------------
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