A node on the secondary surfaces of two ties (a chip's underside and its
sides, a cut face and an outer face) got one constraint per tie. When the
main nodes of one follow the other's main surface, the second constraint is
nearly the first again, and eliminating it divided by round-off: the Pi 5
heat model put 21.9 W more in than its 8 W. Such a node now follows the
main faces of all its ties together (balanced to 5e-11 of the power), a
node following a node that follows it back (a tie each way on one
interface) is an error naming both ties, and a tie row that still nearly
repeats the constraints before it is an error naming them.
mesh.cells ties one way by a fixed order of the cells (hex main to tet)
and makes one tie per tied cell, tie_<cell>, replacing the ties an earlier
run made, so its own ties never hold a node twice.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo
Each secondary node follows the main surface under it as the weighted average
u_A = sum_J (M_AJ / sum_K M_AK) u_J with M_AJ = int psi_A N_J over the reference overlaps and
psi the secondary faces' dual shape functions (Wohlmuth 2000), so the secondary mortar
matrix is diagonal; the rows join the couplings' constraint elimination in every implicit
analysis. Uncovered secondary nodes stay free with a warning; heat transfer and explicit
dynamics refuse ties by name. Tested by the tie patch test on non-matching hex8/tet4 meshes.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo
