Mesh Smoothing

[UZerbinati]

Mesh optimisation options are exposed in ngsPETSc. In particular, this allows to do mesh smoothing.
All details on the mesh optimisation features are available here.
Here is an example:

from firedrake import *
from netgen.occ import *
# Make 2D rectangle from (0, 0) to (1, 2)
rect1 = WorkPlane(Axes((0,0,0), n=Z, h=X)).Rectangle(1,2).Face()
# Make 2D rectangle from (0, 1) to (2, 2)
rect2 = WorkPlane(Axes((0,1,0), n=Z, h=X)).Rectangle(2,1).Face()
L = rect1 + rect2
geo = OCCGeometry(L, dim=2)
ngmesh = geo.GenerateMesh(maxh=0.1)
mesh = Mesh(ngmesh, netgen_flags={"optimisation_moves": "mmmm"})
mh = MeshHierarchy(mesh, 3, netgen_flags={"optimisation_moves": "mmmm"})

[pefarrell]

For quad meshing: is there a way to get netgen to make a quad-native mesh? If not, is there a way to get netgen to make a quad-dominant mesh, and then only split the triangles? I worry this will make for poor-quality meshes.

[UZerbinati]

There is no way to generate a quad only mesh in Netgen.
But I think we might be able to do something to improve the degeneration of the mesh.