add_mesh_sqdIB

[NengLu]

add functions to create the StructuredQuadBox with internal boundary:

• meshing.StructuredQuadBoxInternalBoundary2D
• meshing.StructuredQuadBoxInternalBoundary3D
  add related tests into the test_001_meshes.py

[gthyagi]

@NengLu Here is the code for the unstructured mesh with an internal boundary. Please include this in the PR as well. Note: Be sure to add documentation explaining the purpose of each argument.

if uw.mpi.rank==0 and mesh_type=='unstruct':
    
    import gmsh
    
    # Initialize the Gmsh API
    gmsh.initialize()

    gmsh.option.setNumber("General.Verbosity", 0)
    
    # Create a new model
    gmsh.model.add("2D Unstructured Box with Internal Boundary")
    
    # Add points (corners of the unit box) with the specified cell size
    p1 = gmsh.model.geo.addPoint(xmin, ymin, 0, cellSize)  # Bottom-left corner
    p2 = gmsh.model.geo.addPoint(xmax, ymin, 0, cellSize)  # Bottom-right corner
    p3 = gmsh.model.geo.addPoint(xmax, ymax, 0, cellSize)  # Top-right corner
    p4 = gmsh.model.geo.addPoint(xmin, ymax, 0, cellSize)  # Top-left corner
    
    # Add points for the internal boundary at y = yint
    p5 = gmsh.model.geo.addPoint(xmin, yint, 0, cellSize)  # Left point on internal boundary
    p6 = gmsh.model.geo.addPoint(xmax, yint, 0, cellSize)  # Right point on internal boundary
    
    # Add lines (edges of the unit box and internal boundary)
    l1 = gmsh.model.geo.addLine(p1, p2)  # Bottom edge
    l2_bottom = gmsh.model.geo.addLine(p2, p6)  # Right bottom part
    l2_top = gmsh.model.geo.addLine(p6, p3)  # Right top part
    l3 = gmsh.model.geo.addLine(p3, p4)  # Top edge
    l4_bottom = gmsh.model.geo.addLine(p1, p5)  # Left bottom part
    l4_top = gmsh.model.geo.addLine(p5, p4)  # Left top part
    l_internal = gmsh.model.geo.addLine(p5, p6)  # Internal boundary line at yint
    
    # Create curve loops for the two regions (bottom and top parts of the box)
    cl1 = gmsh.model.geo.addCurveLoop([l1, l2_bottom, -l_internal, -l4_bottom])  # Bottom region
    cl2 = gmsh.model.geo.addCurveLoop([l_internal, l2_top, l3, -l4_top])  # Top region
    
    # Create plane surfaces for both regions
    surface_bottom = gmsh.model.geo.addPlaneSurface([cl1])
    surface_top = gmsh.model.geo.addPlaneSurface([cl2])
    
    # Add physical groups (labels) for the edges using the enum class
    gmsh.model.geo.addPhysicalGroup(1, [l1], tag=boundaries.Bottom.value)  # Bottom
    gmsh.model.setPhysicalName(1, boundaries.Bottom.value, boundaries.Bottom.name)
    
    gmsh.model.geo.addPhysicalGroup(1, [l2_bottom, l2_top], tag=boundaries.Right.value)  # Right
    gmsh.model.setPhysicalName(1, boundaries.Right.value, boundaries.Right.name)
    
    gmsh.model.geo.addPhysicalGroup(1, [l3], tag=boundaries.Top.value)  # Top
    gmsh.model.setPhysicalName(1, boundaries.Top.value, boundaries.Top.name)
    
    gmsh.model.geo.addPhysicalGroup(1, [l4_bottom, l4_top], tag=boundaries.Left.value)  # Left
    gmsh.model.setPhysicalName(1, boundaries.Left.value, boundaries.Left.name)
    
    # Add physical group for the internal boundary at y = yint
    gmsh.model.geo.addPhysicalGroup(1, [l_internal], tag=boundaries.Internal.value)
    gmsh.model.setPhysicalName(1, boundaries.Internal.value, boundaries.Internal.name)
    
    # Add physical groups for the surface (optional)
    gmsh.model.geo.addPhysicalGroup(2, [surface_bottom], tag=6)  # Bottom region surface
    gmsh.model.setPhysicalName(2, 6, "Surface Bottom")
    
    gmsh.model.geo.addPhysicalGroup(2, [surface_top], tag=7)  # Top region surface
    gmsh.model.setPhysicalName(2, 7, "Surface Top")
    
    # Synchronize the internal CAD representation with the Gmsh model
    gmsh.model.geo.synchronize()
    
    # Mesh the surface using unstructured triangles
    gmsh.model.mesh.generate(2)  # 2D mesh
    
    # Optionally save the mesh to a file
    gmsh.write("tmp_mesh.msh")
    
    # # Launch Gmsh GUI to visualize (optional)
    # gmsh.fltk.run()
    
    # Finalize the Gmsh API
    gmsh.finalize()

[NengLu]

Thank Thyagi for mentioning that.

Built the unstructured simplex box with internal boundary into the meshing.BoxInternalBoundary() function, along with the corresponding test cases in test_0001_meshes.py
Now, we can build the following meshes with it:

• structured quadratic box (2D or 3D) with internal boundary
• unstructured simplex box (2D or 3D) with internal boundary

see details in add usbIB mesh

[gthyagi]

@NengLu why did this PR did not pass all checks?

[NengLu]

@NengLu why did this PR did not pass all checks?

I don't have access. This PR is acting as the outside contributor, which needs approval from the maintainer.

[lmoresi]

Looks good to me. You can drop the All_Boundaries = 1001 from the boundary definition as that is now handled automatically in the discretisation code.

[NengLu]

Looks good to me. You can drop the All_Boundaries = 1001 from the boundary definition as that is now handled automatically in the discretisation code.

Thanks, edited.

[lmoresi]

Acknowledging the discussion, I think this can be approved.