Development of multiphysics particle method simulation code PHALSER and its application to various phenomena

Abstract

ABSTRACT A new particle method code called PHALSER (PHysics-based particle AnaLyzer for SEveRe accident) was developed to simulate various phenomena involving phase changes, such as the melting and solidification of materials. One of the main functions is to simulate the behavior of molten materials in a severe accident in a nuclear power plant. In PHALSER, four types of particle (fluid, solid, wall, and discrete element method (DEM) particles) are used to model various situations. The melting and solidification of materials can be simulated by transforming solid particles into fluid particles and vice versa when the melting and solidification conditions are met, respectively. A eutectic reaction can be approximately treated by defining the melting temperature as a function of material composition. A background model was also implemented in PHALSER to define the physical properties of the background, which corresponds to the void area where no particles are allocated, so that the effect of the surrounding phase can be evaluated with a low computational cost. Three calculations on melt spreading, B4C/SS annealing, and spray droplet dissipation were conducted as examples to investigate the applicability of the developed code to these phenomena, and the results were compared with experimental ones for validation.