抄録
Solid-fluid mixture flows formed in a disrupted core of nuclear reactors is one of the key phenomena to be simulated in reactor safety analysis. Their mobility as a mixture is related to effective viscosity increase due to solid-liquid and solid-solid interactions in the mixture. However, regardless of its importance, experimental knowledge is insufficient to clarify its fundamental characteristics. In the present study, a computational framework of fully Lagrangian multiphase flow analysis was developed based on a moving particle method, that is, the finite volume particle method. In this method, assuming that each moving particles occupies a certain control volume, governing equations for fluid dynamics of mixture flows are solved by discretizing their gradient and Laplacian terms using the moving particles. Solid-solid interactions are modeled by the distinct element method, and the solid-fluid ones are represented by the passively moving solid model. The developed computational framework was validated by simulating effective viscosity of a solid-fluid mixture flow, which should increase as a solid fraction increases in the mixture. The simulation results show the same tendency of effective viscosity increase as available theoretical evaluations. This demonstrates the applicability of the present framework to the simulation of solid-liquid mixture flows with effective viscosity increase.
