Geometry-Driven Reconfiguration of Poloidal Recirculating Flow in a Concentric Baffle Vessel
Description
This work presents a complete analytical and structural characterization of steady, incompressible poloidal recirculating flow within a cylindrical vessel equipped with a suspended concentric inner shroud. By treating the diameter ratio λ = D_i / D_o as the governing geometric control parameter, the study demonstrates that internal flow reconfiguration arises not from direct geometric velocity constraints but from systematic redistribution of hydraulic resistances across the core and annulus. Cross-sectional area partitioning, viscous shear, wall friction, and 180° turning losses collectively determine the mean velocity ratio v̄_c / v̄_a, which scales as (R_a / R_c) · ((1 − λ²) / λ²). Extreme geometries (λ ≤ 0.30 or λ ≥ 0.80) generate severe nonlinear choking, producing either high-shear core acceleration or annular compression with elevated skin-friction and turning losses. A mathematically defined optimal region emerges for 0.5 ≤ λ ≤ 0.7, where the velocity ratio approaches unity and total dissipation is minimized. A dimensionless Circulation Efficiency metric, Π = E_k / Φ, is introduced to quantify the balance between integrated kinetic energy and volumetric dissipation. The analytical framework is structurally cross-validated against the ERCOFTAC Classic Collection Case 081 periodic-hill dataset, whose separation, reattachment, and free-shear-layer dynamics mirror the flow-reversal physics at the shroud tips. A standardized CFD validation protocol is provided using a 2D axisymmetric Navier–Stokes solver with SST k–ω turbulence modeling and y⁺ ≤ 1 wall resolution. The resulting model establishes a rigorous, physically grounded baseline for high-fidelity numerical or experimental evaluation of concentric-baffle vessel performance.
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References
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