3D Boundary Layer generation problem

[fil_ita]

Hello,
I am trying to generate a 3D mesh with a Boundary Layer.
If I generate a simple 3D mesh with no boundary layer and no BL parameters, I can manage to generate a good tetrahedral mesh.
However, whenever I add the BL, it seems that additional elements are created, all sharing the origin as common node (at coordinates (0,0,0)).

Can anyone help me, please?
Here is my code snippet:

from ngsolve import *
from netgen import stl

mp = netgen.meshing.MeshingParameters(maxh=6e-4,)
geom = stl.STLGeometry('fluid_DomainExtended_remeshed.stl')
bl = [2.67e-6]  
for i in range(10):
    bl.append(bl[i]*1.1)

bl_p = [netgen.meshing.BoundaryLayerParameters(boundary=".*", thickness = bl, 
                                               #disable_curving=False,
                                               #grow_edges=False,
                                               limit_growth_vectors=True, 
                                               domain=".*",
                                               )]

mesh = geom.GenerateMesh(mp=mp, boundary_layers=bl_p)
mesh.Export(filename='test.mesh', format='Neutral Format',)

Thank you so much in advance for your help.

[fil_ita]

Hello, I am still having this problem. And, it also happens if I am using an STEP File. Can anyone help?

[DarkElektron]

Hi, I tried exporting to other formats with no luck. But saving as a .vol file preserves the boundary layers.

from ngsolve import *
from netgen.occ import *
from ngsolve.webgui import Draw

geom = Glue(OCCGeometry('testcase.step').shape.solids)

bl = [2.67e-2]  
for i in range(11):
    bl.append(bl[i]*1.1)
    
bl_p = [netgen.meshing.BoundaryLayerParameters(boundary='default', thickness = bl, 
                                               #disable_curving=False,
                                               #grow_edges=False,
                                               limit_growth_vectors=True, 
                                               domain=".*",
                                               )]

mesh = geom.GenerateMesh(maxh=0.5, boundary_layers=bl_p)
Draw(mesh)
mesh.ngmesh.Save('test.vol')

Drawing the mesh in ngsolve, I get

Loading the test.vol file in Netgen, I get

PS: I generated a simple box and saved the step file to test your code.