ASSESSMENT OF TURBULENCE MODELS FOR CFD SIMULATION OF PARTIAL FLOW BLOCKAGE IN NUCLEAR FUEL ROD BUNDLES USING LOGOS
Keywords:
CFD, LOGOS, nuclear fuel assembly, partial flow blockage, turbulence modeling, EARSM, rod bundle flow, validation.Abstract
Accurate prediction of coolant flow behavior in nuclear fuel rod bundles under partial flow blockage is essential for reactor safety analysis. This study validates the CFD code LOGOS through simulation of hydrodynamic processes in a 61-rod bundle based on MONJU experimental configurations. Numerical results were compared with experimental velocity measurements to assess turbulence model performance. Calculations were performed using the standard k-ε model and the Explicit Algebraic Reynolds Stress Model (EARSM). The k-ε model reproduces general flow characteristics but fails to adequately predict the recirculation region downstream of the blockage. The EARSM model shows significantly improved agreement with experimental data, particularly in capturing reverse flow behavior. Statistical evaluation confirms higher predictive accuracy of the Reynolds stress–based approach. The results demonstrate the importance of turbulence model selection for reliable CFD-based safety assessment of nuclear fuel assemblies.
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