Issues with "refine hex ... " command at internal boundaries

mneuner · April 16, 2026, 5:39am

EDIT: See second post for a smaller example to demonstrate the issue.

Cubit’s refine hex ... command is an outstanding feature for our research, as it allows us to perform local mesh refinement in areas where we expect strong localization of deformations. Such areas are not necessarily associated with particular geometric features, and hence, local seeding or using extended webcuts are inferior options.

However, I have observed that the refinement algorithm runs into problems when the refinement region crosses internal boundaries of a body. In such cases, the refinement is executed, but the mesh becomes disconnected internally.

Is there any way to resolve this problem?

I have attached a script that generates a model exhibiting this issue, which can also be seen in the screenshot.

github.com

matthiasneuner/Bonded-Anchor-pryout/blob/matthias/refined_model/FE-GCDP-model/Bonded_anchor_edge_breakout_test/mesh/generate_edge_breakout.py

import cubit
import math

# Clear any existing geometry
cubit.cmd("reset")

# --- PARAMETERS ---
# Concrete Slab
slab_x = 200.0        # Total length (x)
slab_z = 300.0        # Total width (z)
slab_h = 160.0        # Total height (y)
edge_dist = 80.0      # Distance from anchor center to the free edge (+x direction)

# Support Conditions
support_w = 40.0      # Width of the support area at the outer corners of the breakout face

# Borehole & Mortar
hole_r = 9.0          # Borehole radius
hole_d = 50.0         # Borehole depth
anchor_d = 50.0       # Depth of the anchor within the borehole (must be <= hole_d)

This file has been truncated. show original

As mentioned, the refinement is done properly, but internally the mesh exhibits “cracks,” and the following error log occurs:

ERROR: generate_edge_breakout.py, line 232. Inconsistent edge to face count relationship.
       ERROR: generate_edge_breakout.py, line 232. Mesh of Surface 40 is invalid.
ERROR: generate_edge_breakout.py, line 232. Refinement process resulted in an invalid surface mesh.
ERROR: generate_edge_breakout.py, line 232. Unable to refine the given list of hexes.
ERROR: generate_edge_breakout.py, line 232. Unable to complete refinement operation on mesh.

mneuner · April 16, 2026, 10:32am

Smaller MWE to reproduce the issue in a simpler setting:

reset
reset aprepro

create cylinder height 10 radius 5

webcut volume all with xplane
imprint volume all
merge volume all

volume all size auto factor 5
mesh volume all

refine hex with x_coord + y_coord < 0.2 * z_coord

advkt_entnschdl · April 16, 2026, 2:49pm

reset
reset aprepro

create cylinder height 10 radius 5

webcut volume all with xplane
imprint volume all
merge volume all

volume all size auto factor 5
mesh volume all

refine hex with x_coord + y_coord < 0.2 * z_coord

By disassociating the mesh from its parent geometry after meshing

disassociate mesh from volume all

the elements can be refined without problems.

However, this creates problems downstream, as entity selection (nodes, faces, …) via the parent geometry is not possible anymore.