Modal analysis of lead-bismuth eutectic flow in a single wire-wrapped rod channel

The thermal-hydraulics as well as flow-induced vibration of wire-wrapped rod bundles calls for accurate and efficient liquid metal flow simulation and prediction, yet it remains a challenge due to the complex geometries and high Reynolds number flow in wire-wrapped rod channel. Previous efforts towards this goal exclusively adopts full-order modeling (FOM), which is prohibitively computation-intensive. This work reports the first reference on modal analysis of the turbulent lead-bismuth eutectic (LBE) flow in a single wire-wrapped rod channel by a data-driven dynamic mode decomposition (DMD) method. The spatio-temporal data of fluid velocities and pressure were modeled and collected by using the Reynolds-averaged Navier–Stokes equations (RANS) approach with stress-omega RSM turbulence model. Modal analysis was performed over the snapshot matrices and DMD modes and corresponding eigenvalues were calculated. The DMD modes and eigenvalues were then used to construct a reduced-order modeling (ROM) system for fast fluid field reconstruction and short-term forecasting. The correctness and feasibility of the method was demonstrated and compared with ground-truth CFD simulation results. Our method offers a fast and reliable approach for ROM of turbulent flow in wire-wrapped rod fuel assemblies. We publicize all the data and codes via https://github.com/XJTU-Zhou-group/Wire-wrapped-fuel-pin-CFD-DMD.