Radioactive particle migration from the soil surface is an unignorable factor for the radioactive material distribution prediction after a nuclear accident, especially for the decision support of radioactive disposal. Considering the continuous emission, collision, and reattachment of radioactive particles, a creative simulation method with a coupled model was proposed, which combines an empirical model and the CFD-DEM method, and was established to simulate the secondary emission and motion of radioactive particles. The source term of the radioactive particles is estimated by an empirical model as the input of the CFD-DEM. Regarding the characteristics of the particle motion, the spout-fluidized bed simulation by the coupled model is consistent with the referred simulation results and experimental data, which validates the correctness of this model. The coupling model was applied to simulate the radioactive particle distribution and migration on the nonconfined backward facing step (NBFS). The simulation reveals that the distribution features and migration flux of the radioactive particles can be estimated in detail by the proposed model, which can help to provide more actual information for radioactive disposal after nuclear accidents.

中文翻译：

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使用 CFD-DEM 结合经验公式对大气环境中放射性土壤粒子的迁移模拟

放射性粒子从土壤表面迁移是核事故后放射性物质分布预测不可忽视的因素，尤其是对放射性处置的决策支持。针对放射性粒子的连续发射、碰撞和再附着，提出了一种创新的耦合模型模拟方法，将经验模型与CFD-DEM方法相结合，建立了对放射性粒子二次发射和运动的模拟。放射性颗粒的源项由经验模型估算，作为CFD-DEM的输入。关于粒子运动的特性，通过耦合模型进行的射流流化床模拟与参考的模拟结果和实验数据一致，验证了这个模型的正确性。耦合模型用于模拟放射性粒子在无约束后向台阶（NBFS）上的分布和迁移。仿真结果表明，该模型可以详细估计放射性粒子的分布特征和迁移通量，有助于为核事故后的放射性处置提供更多的实际信息。