TRIDENT Mini Case Card — Boundary-Driven Instability and Threshold Pattern Formation: Rayleigh–Bénard Convection (PHYS-RBC-001.v1)

This mini case card applies the TRIDENT-Z0 diagnostic framework to Rayleigh–Bénard convection as a clean example of boundary-driven instability and threshold-induced pattern formation. A horizontal fluid layer heated from below develops organized convection rolls once the Rayleigh number exceeds the critical value Ra_c ≈ 1708 (for rigid boundaries). Below this threshold, the system remains in a purely conductive state. The analysis evaluates the phenomenon through four gates (Bulk Lock, Boundary Flow, Constraint Field, Coherence Dependency). G1–G3 pass cleanly: the instability is experimentally robust, mechanistically well-defined via buoyancy-driven flow under thermal gradients, and mathematically constrained…