Boundary Leakage

Unintended loss or artificial flux of conserved quantities (mass, energy, momentum, probability, etc.) across a nominal boundary in a simulation or discretized model caused by discretization errors, inconsistent coupling, ghost-cell treatments, or incorrect numerical fluxes.

The unintended transfer of duties, information, resources, regulatory effects, or externalities across a formally intended institutional, legal, or organizational boundary, so that separations designed to limit interaction are compromised in practice.