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.

摘要

开发了一种称为 PHALSER（用于 SEveRe 事故的基于物理学的粒子分析仪）的新粒子方法代码，用于模拟涉及相变的各种现象，例如材料的熔化和凝固。主要功能之一是模拟核电厂严重事故中熔融材料的行为。在 PHALSER 中，四种类型的粒子（流体、固体、壁和离散元方法 (DEM) 粒子）用于模拟各种情况。当分别满足熔化和凝固条件时，可以通过将固体颗粒转化为流体颗粒来模拟材料的熔化和凝固，反之亦然。可以通过将熔化温度定义为材料成分的函数来近似处理共晶反应。在 PHALSER 中还实现了一个背景模型来定义背景的物理属性，它对应于没有分配粒子的空隙区域，以便可以以较低的计算成本评估周围相的影响。熔体铺展的三种计算，B_{以 4} C/SS 退火和喷雾液滴消散为例，研究开发的代码对这些现象的适用性，并将结果与​​实验结果进行比较以进行验证。