From: David Wells Date: Sun, 22 Apr 2018 21:12:08 +0000 (-0400) Subject: Update basic Manifold usage in the examples. X-Git-Tag: v9.0.0-rc1~136^2 X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6294e33b9352db53a54bc48a21e4273890e57012;p=dealii.git Update basic Manifold usage in the examples. --- diff --git a/examples/step-1/doc/intro.dox b/examples/step-1/doc/intro.dox index b87312bda3..8e6414f3b3 100644 --- a/examples/step-1/doc/intro.dox +++ b/examples/step-1/doc/intro.dox @@ -133,8 +133,9 @@ development we occasionally rename or deprecate functions or classes that are still referenced in these video lectures. For example, the step-1 code shown in video lecture 5 uses a class HyperShellBoundary which was replaced with SphericalManifold class -later on. However, in spite of such kind of details the content of the -lectures is still very relevant. +later on. Additionally, as of deal.II version 9.0, GridGenerator::hyper_shell() +now automatically attaches a SphericalManifold to the Triangulation. Otherwise +the rest of the lecture material is relevant.

What this program does

diff --git a/examples/step-1/doc/results.dox b/examples/step-1/doc/results.dox index 3b783bd5fa..8a1f31d3b7 100644 --- a/examples/step-1/doc/results.dox +++ b/examples/step-1/doc/results.dox @@ -53,11 +53,21 @@ Another possibility would be to generate meshes of entirely different geometries altogether. While for complex geometries there is no way around using meshes obtained from mesh generators, there is a good number of geometries for which deal.II can create meshes using the functions in the -GridGenerator namespace. Take a look at what it provides and see how it could -be used in a program like this. - -We also discuss a variety of other ways to create and manipulate meshes to -step-49. +GridGenerator namespace. Many of these geometries (such as the one used in this +example program) contain cells with curved faces: put another way, we expect the +new vertices placed on the boundary to lie along a circle. deal.II handles complex +geometries with the Manifold class (and classes inheriting from it); in particular, +the functions in GridGenerator corresponding to non-Cartesian grids (such as +GridGenerator::hyper_shell or GridGenerator::truncated_cone) attach a Manifold +object to the part of the triangulation that should be curved (SphericalManifold +and CylindricalManifold, respectively) and use another manifold on the parts that +should be flat (FlatManifold). See the documentation +of Manifold or the @ref manifold "manifold module" for descriptions of the design +philosophy and interfaces of these classes. Take a look at what they provide and +see how they could be used in a program like this. + +We also discuss a variety of other ways to create and manipulate meshes (and +describe the process of attaching Manifolds) in step-49.

Comments about programming and debugging

diff --git a/examples/step-1/step-1.cc b/examples/step-1/step-1.cc index 6ec5b28097..eae68f7cd9 100644 --- a/examples/step-1/step-1.cc +++ b/examples/step-1/step-1.cc @@ -105,7 +105,7 @@ void second_grid () // straight lines, and all cells are bi-linear quads or tri-linear // hexes, and that they are defined by the cells of the coarse grid // (which we just created). Unless we do something special, when new - // points need to be introduced; the domain is assumed to be + // points need to be introduced the domain is assumed to be // delineated by the straight lines of the coarse mesh, and new // points will simply be in the middle of the surrounding ones. // Here, however, we know that the domain is curved, and we would @@ -120,9 +120,18 @@ void second_grid () // triangulation to use a particular "manifold object" for all // places with this manifold indicator. How exactly this works is // not important at this point (you can read up on it in step-53 and - // @ref manifold). Here, for simplicity, we will choose the manifold - // id to be zero. By default, all cells and faces of the - // Triangulation have their manifold_id set to + // @ref manifold). The functions in GridGenerator handle this for us in most + // circumstances: they attach the correct manifold to a domain so that when + // the triangulation is refined new cells are placed in the correct + // places. In the present case GridGenerator::hyper_shell attaches a + // SphericalManifold to all cells: this causes cells to be refined with + // calculations in spherical coordinates (so new cells have edges that are + // either radial or lie along concentric circles around the origin). + // + // By default (i.e., for a Triangulation created by hand or without a call + // to a GridGenerator function like GridGenerator::hyper_shell or + // GridGenerator::hyper_ball), all cells and + // faces of the Triangulation have their manifold_id set to // numbers::invalid_manifold_id, which is the default if you want a // manifold that produces straight edges, but you can change this // number for individual cells and faces. In that case, the curved @@ -134,11 +143,9 @@ void second_grid () // edges is implied. (Manifold indicators are a slightly complicated // topic; if you're confused about what exactly is happening here, // you may want to look at the @ref GlossManifoldIndicator "glossary - // entry on this topic".) - const SphericalManifold<2> manifold_description(center); - triangulation.set_manifold (0, manifold_description); - triangulation.set_all_manifold_ids(0); - + // entry on this topic".) Since the default chosen by + // GridGenerator::hyper_shell is reasonable we leave things alone. + // // In order to demonstrate how to write a loop over all cells, we will // refine the grid in five steps towards the inner circle of the domain: for (unsigned int step=0; step<5; ++step) diff --git a/examples/step-16/step-16.cc b/examples/step-16/step-16.cc index 46a06dfbbd..4ca9294d47 100644 --- a/examples/step-16/step-16.cc +++ b/examples/step-16/step-16.cc @@ -613,11 +613,6 @@ namespace Step16 if (cycle == 0) { GridGenerator::hyper_ball (triangulation); - - static const SphericalManifold boundary; - triangulation.set_all_manifold_ids_on_boundary(0); - triangulation.set_manifold (0, boundary); - triangulation.refine_global (1); } else diff --git a/examples/step-2/step-2.cc b/examples/step-2/step-2.cc index 05e00c8c27..fdedf43757 100644 --- a/examples/step-2/step-2.cc +++ b/examples/step-2/step-2.cc @@ -66,18 +66,6 @@ using namespace dealii; // This is the function that produced the circular grid in the previous step-1 // example program with fewer refinements steps. The sole difference is that it // returns the grid it produces via its argument. -// -// The details of what the function does are explained in step-1. The only -// thing we would like to comment on is this: -// -// Since we want to export the triangulation through this function's -// parameter, we need to make sure that the manifold object lives at least as -// long as the triangulation does. However, in step-1, the manifold object is -// a local variable, and it would be deleted at the end of the function, which -// is too early. We avoid the problem by declaring it 'static' which makes -// sure that the object is initialized the first time control the program -// passes this point, but at the same time assures that it lives until the end -// of the program. void make_grid (Triangulation<2> &triangulation) { const Point<2> center (1,0); @@ -87,10 +75,6 @@ void make_grid (Triangulation<2> &triangulation) center, inner_radius, outer_radius, 5 ); - static const SphericalManifold<2> manifold_description(center); - triangulation.set_manifold (0, manifold_description); - triangulation.set_all_manifold_ids(0); - for (unsigned int step=0; step<3; ++step) { for (auto cell: triangulation.active_cell_iterators()) diff --git a/examples/step-24/step-24.cc b/examples/step-24/step-24.cc index c97e9dd8f2..2375013f90 100644 --- a/examples/step-24/step-24.cc +++ b/examples/step-24/step-24.cc @@ -274,9 +274,6 @@ namespace Step24 { const Point center; GridGenerator::hyper_ball (triangulation, center, 1.); - static const SphericalManifold boundary_description (center); - triangulation.set_all_manifold_ids_on_boundary(0); - triangulation.set_manifold (0,boundary_description); triangulation.refine_global (7); time_step = GridTools::minimal_cell_diameter(triangulation) / diff --git a/examples/step-29/step-29.cc b/examples/step-29/step-29.cc index 3ba142e48a..b08ed0f08b 100644 --- a/examples/step-29/step-29.cc +++ b/examples/step-29/step-29.cc @@ -486,12 +486,8 @@ namespace Step29 } // For the circle part of the transducer lens, a SphericalManifold object // is used (which, of course, in 2D just represents a circle), with center - // computed as above. By marking this object as static, we - // ensure that it lives until the end of the program and thereby longer - // than the triangulation object we will associate with it. We then assign - // this boundary-object to the part of the boundary with boundary indicator 1: - static const SphericalManifold boundary(focal_point); - triangulation.set_manifold(1, boundary); + // computed as above. + triangulation.set_manifold(1, SphericalManifold(focal_point)); // Now global refinement is executed. Cells near the transducer location // will be automatically refined according to the circle shaped boundary diff --git a/examples/step-42/step-42.cc b/examples/step-42/step-42.cc index 39612f0b51..f888604a88 100644 --- a/examples/step-42/step-42.cc +++ b/examples/step-42/step-42.cc @@ -923,11 +923,14 @@ namespace Step42 const Point center(0, 0, 0); const double radius = 0.8; GridGenerator::half_hyper_ball(triangulation, center, radius); + // Since we will attach a different manifold below, we immediately + // clear the default manifold description: + triangulation.reset_all_manifolds(); GridTools::transform(&rotate_half_sphere, triangulation); GridTools::shift(Point(0.5, 0.5, 0.5), triangulation); - static SphericalManifold manifold_description(Point(0.5, 0.5, 0.5)); + SphericalManifold manifold_description(Point(0.5, 0.5, 0.5)); GridTools::copy_boundary_to_manifold_id(triangulation); triangulation.set_manifold(0, manifold_description); } diff --git a/examples/step-45/step-45.cc b/examples/step-45/step-45.cc index 145a88389f..bbf0baff2d 100644 --- a/examples/step-45/step-45.cc +++ b/examples/step-45/step-45.cc @@ -85,7 +85,6 @@ namespace Step45 MPI_Comm mpi_communicator; - SphericalManifold manifold; parallel::distributed::Triangulation triangulation; FESystem fe; DoFHandler dof_handler; @@ -350,9 +349,6 @@ namespace Step45 // parallel::distributed::Triangulation::add_periodicity. triangulation.add_periodicity(periodicity_vector); - triangulation.set_all_manifold_ids(1); - triangulation.set_manifold(1, manifold); - triangulation.refine_global (4-dim); } diff --git a/examples/step-47/step-47.cc b/examples/step-47/step-47.cc index 1bf8da6d31..b2f8920dad 100644 --- a/examples/step-47/step-47.cc +++ b/examples/step-47/step-47.cc @@ -1061,11 +1061,6 @@ namespace Step47 { GridGenerator::hyper_ball (triangulation); //GridGenerator::hyper_cube (triangulation, -1, 1); - - static const SphericalManifold boundary; - triangulation.set_all_manifold_ids_on_boundary(0); - triangulation.set_manifold (0, boundary); - triangulation.refine_global (2); } else