How Pygmsh mesh a .*vtu file created by meshio?

[SamTAOUM]

Hello,
I create a mesh with pygmsh that I change the coordinates of the points of mesh to my topologie of study.
I'm working to developp a FEM software on geophysics. I want to create mesh of order 2 or 3 for FEM.
The problem that I can't mesh it directly on order 2 by using " generate_mesh(geom, extra_gmsh_arguments=["-order", "2"])", cause the coordinates of points will be changed and than I lost the form of tetra10 in my mesh.
In GMSH, we can save than open a .msh file than mesh it into order 2. I'm looking to do the same in pygmsh using meshio. So my code:

_ first mesh

points, cells, ...= pygmsh.generate_mesh(geom, extra_gmsh_arguments=["-order", "1"])

_change coordinates of points (points--->newpoints)

_write vtu file with meshio

meshio.write_points_cells("mymesh.vtu",newpoints,cells,cell_data=cell_data)

how can I generate mesh to mymesh.vtu using pygmsh?

points, cells, ...= pygmsh.generate_mesh("mymesh.vtu", extra_gmsh_arguments=["-order", "2"])

??

[nschloe]

cause the coordinates of points will be changed and than I lost the form of tetra10 in my mesh.

I don't understand what that means.

how can I generate mesh to mymesh.vtu using pygmsh?

What's the problem? You already described how to do it.

[SamTAOUM]

Hello

points, cells, ...= pygmsh.generate_mesh("mymesh.vtu", extra_gmsh_arguments=["-order", "2"])

doesn't work. AttributeError: 'str' object has no attribute 'get_code'

[nschloe]

Well you need to provide a geometry, right?

[SamTAOUM]

yes exactly

[nschloe]

Yeah so why don't you do it? You're using generate_mesh wrong.

[SamTAOUM]

I tried:

geom_1 = pygmsh.built_in.Geometry()
geom_1.add_raw_code( "mymesh.vtu")
points, cells, point_data, cell_data, field_data = pygmsh.generate_mesh(geom_1, extra_gmsh_arguments=["-order", "2"])

but doesn't work

[nschloe]

This

geom_1.add_raw_code( "mymesh.vtu")

doesn't make any sense at all. "mymesh.vtu" is not a valid gmsh command. I don't understand what you're trying to do.

[SamTAOUM]

I'm trying to do like Gmsh, by opening a .*msh file to mesh it again on order 2.
I used here meshio to write "mymesh.vtu"
I want to open and read the file "mymesh.vtu" to mesh it again with generate_mesh

[SamTAOUM]

hope, I explained clearly the problem

[nschloe]

by opening a .*msh file to mesh it again on order 2.

pygmsh cannot read meshes. You can only create a geometry and mesh that.

[SamTAOUM]

Okay, thank you for your explaination.
I'll try another solution to mesh my topologie of study on order 2 and 3.