On Wed, 11 Apr 2018, 서승진 wrote:
1) In visualization, I used paraview and open out_2.e (in introduction_ex4). The paraview displayed the white box. I think that this is mesh for the example. However, paraview didn't displayed the solution distribution (colored box). Is the problem is come from the absence of post-processing in the example?
Did you tell paraview to display the solution distribution? When I first open out_2.e in paraview 5.0.1, it displays nothing. When I then click on the Properties->Variables->u checkbox and hit Apply, it displays a white box (the domain for the example). When I then change from "vtkBlockColors" to "u" in the active variable controls toolbar, it displays a box colored by the solution.
I understood that Libmesh examples use Dirichlet condition, and the part to set boundary condition is; std::set<boundary_id_type> boundary_ids; boundary_ids.insert(0); boundary_ids.insert(1); boundary_ids.insert(2); boundary_ids.insert(3); DirichletBoundary dirichlet_bc(boundary_ids, variables, exact_solution_object); system.get_dof_map().add_dirichlet_boundary(dirichlet_bc);
However, I couldn't find the part to set the initial value of u_var and value of boundary condition for each boundary.ids... How I can set the value of initial condition and boundary conditions?
"exact_solution_object" in the above code is the functor which returns boundary condition values. Initial condition values are typically set with System::project_solution(). See transient_ex1.C for an example.
3) In mailing list, some people mentioned about the example which contain Neumann boundary condition with penalty method,
This sounds confused. The penalty method sets a Robin boundary condition which is closely related to a desired Dirichlet boundary condition, it's not for Neumann boundary conditions.
so I've searched the example in Libmesh, but I couldn't find. Is there no neumann B.C. example in Libmesh?
systems_of_equations_ex2.C, if you modify it to use the set_stagnation_bcs() function, has a homogeneous Neumann outflow condition. fem_system_ex4.C has a homogeneous Neumann condition on one side. But homogeneous Neumann in most finite element formulations means "do nothing", so if you have a heterogeneous Neumann boundary you probably still want an example... let's see. miscellaneous_ex9.C uses a constant Neumann flux = 1 on one domain side. systems_of_equations_ex4.C (and _ex5.C, and _ex6.C...) use a constant Neumann traction on one side.
Thanks for reading my email. For your answer, I successfully installed the libmesh.
You're welcome. You should probably join and send future emails to libmesh-users, though; that way they might not languish without reply quite as long when I'm busy. --- Roy ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Libmesh-users mailing list Libmesh-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-users
