Heat Transfer Correlations and Flow-Mode Transitions in Partitioned Cavities for Efficient Thermal Management

Partitioned cavities are widely used in passive, compact thermal management systems (data-center liquid cooling, cryogenic hydrogen/LNG storage, and battery modules) where geometric confinement governs natural convection and heat transfer. This study examines buoyancy-driven convection using a two-dimensional steady laminar model with adiabatic partitions under the Boussinesq approximation over Ra = 103 to 106, partition heights H = 0.1–0.9, and partition numbers N = 0–7. The model is validated against benchmark data. Flow fields are categorized into four modes—single circulation, corner vortices, secondary vortices, and stagnant flow—and their combinations, yielding an integrated flow-mode map that captures regimes and transitions. Two transition mechanisms are identified: slot-scale transitions driven by nonlinear changes in localized vortices and partition-dominated transitions that reorganize the primary circulation. Thermal-field analysis shows how partitions reshape temperature stratification, while the dependence of the Nusselt number on flow modes and geometric parameters is quantitatively analyzed. Quantitatively, strong confinement (H = 0.9, N ≥ 6) reduces global heat transfer by 75–85%, reaching 98% at Ra = 106. Intermediate partitions (H ≈ 0.5, N = 3–4) yield 40–60% reduction. Shallow partitions (H ≤ 0.3) cause