An improved MPS-DEM numerical model for fluid–solid coupling problem in nuclear reactor.

• The idea of multiphase flow is introduced into the MPS-DEM numerical model for fluid–solid coupling problem for the first time. • Reproduce the DKT phenomenon to validate the improved MPS code. • Simulate the slide of dry granular material and the underwater landslide problem and compare the numerical results with the experimental results and simulate the molten pool accumulation successful. Compared with the grid method, the moving particle semi-implicit method (MPS) has prominent advantages in capturing the phase interface and avoiding grid distortion at the interface. However, MPS method is not particularly effective in dealing with the fluid–solid coupling problems including the interaction between discrete solid elements. Therefore, the PArticle method software for Nuclear reactor thermal hyDraulic Analysis (PANDA) is developed based on the MPS method and coupled Discrete Element Method (DEM) by introducing the idea of multiphase flow into the MPS-DEM coupling method. In this paper, the model is validated by reappearing the phenomena of DKT(drafting, kissing, and tumbling), and the problems of the slide of dry granular material and the underwater landslide are simulated as well. The numerical results are in good agreement with the experimental results, and the relative error of the leading edge distance is less than 6.12%. Finally, numerical simulation is carried out by taking molten pool accumulation in sereve accident of nuclear reactor as an example, which further confirms the good application prospects of PANDA in engineering problems. [ABSTRACT FROM AUTHOR]