Stationary FLD with derived flux and analytic linear diffusion-limit references. Differences include nonlinear-limiter and boundary-model effects; reported norms cover the projected slice, not the full volume.
Stationary FLD compared with its analytic linear diffusion-limit reference. The reference is not exact for the nonlinear limiter. Flux remains derived; no separate momentum conservation test applies.
Central cell layer at z=dx/2; ray at y=z=dx/2.


