Creating a mesh

1. Load a mesh from a geo or msh file

feelpp.mesh(dim=2, geo=1, realdim=2, worldComm=None) : create a mesh. The mesh is of topological dimension dim, in real dimension realdim with geometric order geo. The mesh is configured with a WorldComm which provides the parallel process layout.

Keyword arguments:

  • dim : the topological dimension (default: 2)

  • geo : the geometrical order (default: 1)

  • realdim : the real dimension (default: 2)

  • worldComm : the parallel communicator for the mesh (default: Environment::worldCommPtr())

feelpp.load(m, path, size) → feelpp._mesh.Mesh_S1DG1R1 : load a mesh from a file

  • m declared with the function mesh above

  • path (string) path to the geometry (with geo or msh format)

  • size (float) size of the meshed geometry (if it is not meshed yet)

Example
m = feelpp.mesh(dim=3, realdim=3)
mesh = feelpp.load(m, "path/to/file", 0.1)

2. Usage

The mesh provides the Feel++ data structures in Python: The following methods are to use on the mesh object (mesh in the previous example) :

2.1. Mesh information :

  • dimension(self) → int : get topological dimension

  • hAverage(self) → float : get the average edge length of the mesh

  • hMax(self) → float : get the maximum edge length of the mesh

  • hMin(self) → float : get the minimum edge length of the mesh

  • measure(self, parallel: bool = True) → float : get the measure of the mesh (which is equal to \(\int_\Omega 1\))

  • measureBoundary(self) → float : get the measure of the boundary of the mesh (which is equal to \(???\))

  • numGlobalEdges(self) → int : get the number of edges over the whole mesh, requires communication if the mesh is parallel

  • numGlobalElements(self) → int : get the number of elements over the whole mesh, requires communication if the mesh is parallel

  • numGlobalFaces(self) → int : get the number of faces over the whole mesh, requires communication if the mesh is parallel

  • numGlobalPoints(self) → int : get the number of points over the whole mesh, requires communication if the mesh is parallel

  • realDimension(self) → int : get real dimension

  • updateMeasures(self) → None : update the measures of the mesh

2.2. Test relation between meshes :

  • isParentMeshOf(self: feelpp._mesh.Mesh_S3DG1R3, arg0: feelpp._mesh.Mesh_S3DG1R3) → bool : is the mesh the parent mesh of another mesh

  • isRelatedTo(self: feelpp._mesh.Mesh_S3DG1R3, arg0: feelpp._mesh.Mesh_S3DG1R3) → bool : is the mesh related to another mesh

  • isSiblingOf(self: feelpp._mesh.Mesh_S3DG1R3, arg0: feelpp._mesh.Mesh_S3DG1R3) → bool: is the mesh a sibling of another mesh

  • isSubMeshFrom(self: feelpp._mesh.Mesh_S3DG1R3, arg0: feelpp._mesh.Mesh_S3DG1R3) → bool : is the mesh a sub mesh of another mesh

2.3. Export and load mesh on HDF5 format

  • saveHDF5(self, name: str) → None : save mesh to H5 file

  • loadHDF5(self, name: str) → None : load mesh from H5 file

3. Ranges

  • elements : feelpp.elements(mesh) : get iterator over the elements of the mesh

  • markedelements :

    1. feelpp.markedelements(mesh, tag: str) : get iterator over the marked elements of the mesh

    2. feelpp.markedelements(mesh, marker: str) : return the range of elements of the mesh with marker

    3. feelpp.markedelements(mesh, markers: List[str]) : return the range of elements of the mesh with markers

  • faces (???)

  • markedfaces :

    1. feelpp.markedfaces(mesh, marker: str) : return the range of facets of the mesh with marker

    2. markedfaces(mesh, markers: List[str]) : return the range of facets of the mesh with marker

  • boundaryfaces : feelpp.boundaryfaces(mesh): get iterator over the boundary faces of the mesh

Example : compute integrals
from feelpp.integrate  import integrate

i1 = integrate(range=feelpp.elements(mesh),expr="sin(x+y):x:y")
i2 = integrate(range=feelpp.boundaryfaces(mesh),expr="x*nx+y*ny+z*nz:x:y:z:nx:ny:nz")
i3 = integrate(range=feelpp.markedelements(mesh, "marker"), expr="1")

4. Complete example

Mesh data structure handling example
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