Thanks for your code. I am the beginnder of c++, still trying to
understand them.
On 8/11/08, Roy Stogner <[EMAIL PROTECTED]> wrote:
>
>
> On Mon, 11 Aug 2008, yunfei zhu wrote:
>
> Hi, could you guys tell me which function can be used to mesh a
>> thick-walled cylinder? In the file of mesh_generation.h, there are
>> functions: void build_cube(), void build_line (), void
>> build_square(), void build_sphere(). Do you have some function like
>> build_cylinder()? or some other method to mesh a cylinder? Many
>> thanks.
>>
>
> I've got some code I wrote for another local libMesh user, but I
> never tested it enough to want to put it in the library. I'll copy
> the relevant parts here, but buyer beware. If you need child element
> nodes to be snapped to the correct geometry after refinement, you'll
> have to do that yourself. If you need documentation, please write
> some and email us a copy. If this code breaks, you get to keep both
> pieces.
>
> ---
>
> else if (param.domaintype == "square" || param.domaintype == "cylinder")
> {
> if (param.dimension == 1)
> MeshTools::Generation::build_line
> (mesh, param.coarsegridx,
> param.domain_xmin, param.domain_xmin + param.domain_edge_width,
> EDGE2);
> else if (param.dimension == 2)
> {
> if (param.elementtype == "unstructured")
> {
> MeshTools::Generation::build_delaunay_square
> (mesh, param.coarsegridx, param.coarsegridy,
> param.domain_xmin, param.domain_xmin +
> param.domain_edge_width,
> param.domain_ymin, param.domain_ymin +
> param.domain_edge_length
> ,
> TRI3);
> }
> else
> MeshTools::Generation::build_square
> (mesh, param.coarsegridx, param.coarsegridy,
> param.domain_xmin, param.domain_xmin +
> param.domain_edge_width,
> param.domain_ymin, param.domain_ymin +
> param.domain_edge_length,
> elemtype);
> }
> else if (param.dimension == 3)
> {
> if (param.elementtype == "tri")
> libmesh_error();
> MeshTools::Generation::build_cube
> (mesh, param.coarsegridx, param.coarsegridy, param.coarsegridz,
> param.domain_xmin, param.domain_xmin + param.domain_edge_width,
> param.domain_ymin, param.domain_ymin +
> param.domain_edge_length,
> param.domain_zmin, param.domain_zmin +
> param.domain_edge_height,
> HEX8);
> }
> else
> libmesh_error();
> }
>
> ...
>
> if (param.domaintype == "cylinder")
> {
> if (param.domain_ymin != 0.0 ||
> param.domain_edge_length != 1.0)
> {
> std::cerr << "Theta must range from 0 to 1"
> << std::endl;
> libmesh_error();
> }
>
> PointLocatorTree point_locator(mesh);
>
> MeshBase::element_iterator el = mesh.elements_begin();
> const MeshBase::element_iterator end_el = mesh.elements_end();
>
> for (; el != end_el; ++el)
> {
> Elem* elem = *el;
>
> // The boundary we sew up causes problems with BoundaryInfo
> // later, so for now remove all boundary ids
> mesh.boundary_info->remove(elem);
>
> for (unsigned int n = 0; n != elem->n_nodes(); ++n)
> {
> Node &node = *(elem->get_node(n));
> if (std::abs(node(1) - param.domain_edge_length) < TOLERANCE)
> {
> Point wrapped_point = node;
> wrapped_point(1) = 0;
> Elem *wrapped_elem =
> const_cast<Elem *>(point_locator(wrapped_point));
> libmesh_assert(elem);
>
> bool found_matching_point = false;
> for (unsigned int wn = 0; wn != wrapped_elem->n_nodes();
> ++wn)
> {
> Node *new_node = wrapped_elem->get_node(wn);
> if (new_node->absolute_fuzzy_equals(wrapped_point))
> {
> elem->set_node(n) = new_node;
> found_matching_point = true;
> break;
> }
> }
> libmesh_assert(found_matching_point);
> }
> }
> }
>
> MeshBase::node_iterator nd = mesh.nodes_begin();
> const MeshBase::node_iterator end_nd = mesh.nodes_end();
> if (param.dimension == 3 || param.dimension == 2)
> {
> for (; nd != end_nd; ++nd)
> {
> Node &node = **nd;
> Real r = node(0), theta = node(1); //, z = node(2);
> node(0) = r * cos(2.0*M_PI*theta);
> node(1) = r * sin(2.0*M_PI*theta);
> // node(2) = z;
>
> // The boundary we sew up causes problems with
> // BoundaryInfo later, so for now remove all boundary
> // ids
> mesh.boundary_info->remove(&node);
>
> }
> }
> else
> {
> libmesh_error();
> }
> }
>
>
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