Study on multi-scale coupled uncertainty analysis method based on preCICE

BackgroundCurrent research on multi-scale coupling primarily focuses on code development and verification, while systematic studies addressing uncertainties in coupled codes remain scarce.PurposeThis study aims to construct a multi-scale coupled uncertainty analysis code based on the open-source coupling framework preCICE for uncertainty quantification in multi-physics coupled simulations.MethodsFirstly, the Computational Fluid Dynamics (CFD) code FLUENT, the subchannel code SUBCHANFLOW, and the uncertainty quantification module DAKOTA were integrated into the open-source coupling library preCICE-based development of a multi-scale coupled uncertainty analysis program. Then, numerical verification under steady-state and transient conditions was conducted by establishing a 3×3 rod bundle model, and implemented uncertainty quantification and sensitivity analysis for multi-physics coupling systems.ResultsExperimental data demonstrate that: 1) The axial temperature distribution of the coupled system under steady-state conditions closely matches the computational results from single-code simulations; 2) In transient verification, outlet mass flow rate fluctuations exhibit perfect synchronization in both period and phase under sinusoidal perturbation of inlet mass flow rate conditions; 3) Uncertainty quantification reveals that key parameters including coolant temperature and peak cladding temperature follow a normal distribution pattern; 4) Sensitivity analysis identifies inlet mass flow rate, outlet pressure, inlet temperature, and fuel rod heat flux as dominant factors governing system responses.ConclusionsThe findings of this study validate the response reliability of the multi-scale coupled system under dynamic operational conditions, providing critical technical support for the application of multi-physics coupling methodologies in nuclear safety analysis.