Shengli Xu schrieb:
> In example 8 :
> ......
> if (fabs(curr_node(2)z_coo) < TOLERANCE)
> {
> // The global number of the respective degree of freedom.
> unsigned int dn = curr_node.dof_number(0,0,0);
>
> // The penalty parameter.
> const Real penalty = 1.e10;
> ......
>
> the function dof_number(0,0,0) is unsigned int
> DofObject::dof_number(const unsigned int s, const unsigned int var,
> const unsigned int comp). What is comp? Is it for parallel?
Comp is the number of components (for variable var in system s)
associated with a specific DofObject. For the Lagrange elements
used here, each node has exactly one degree of freedom (and
ther is only one variable), which means that there is only one
component (0) and we get the corresponding
dof number from the call dof_number(0,0,0).
Note that for other finite element types more than one degree of
freedom can be associated
with one node, and there can also be dofs that belong to elements.
> For example in 2D , the first defined variable is u, the second defined
> variable is v. If I want to set the boundary of v. Is it right that
> dof_number(0,1,0)?
Yes.
> Can libMesh read boundary information from input file? What is the
> format ? Is there some examples about it?
> Can libMesh read all information from input file. Don't set the node
> boundary condition like in Example 8 manually.
You may have a look at example 7.
In this example the rhs vector is read from a file. In
a similar manner other boundary conditions can be defined
in such an input file.
Steffen
