A Study of phase-field parameters in gas-liquid two-phase flow problems

Sugihara, Kenta ; Onodera, Naoyuki   ; Idomura, Yasuhiro   ; Yamashita, Susumu   

A multi-phase multi-component thermal-hydraulic simulation code JUPITER has been developed to analyze the molten material behavior under severe accident conditions in nuclear reactors. In JUPITER, the THINC/WLIC method was implemented as an interface tracking method, which enabled us to accurately calculate the dynamics of the multiphase interface of the molten material at relatively low flow velocity. However, when JUPITER is applied to air-water two phase flows in fuel bundles, there is a problem that the Volume of Fluid (VOF) value is stripped from the interface and small VOF values drift in turbulent flows where coalescence and separation of the interface are active. To improve the interface tracking method of the JUPITER code, the applicability of the phase-field method has been investigated. In this study, the phase-field method is applied to the JUPITER code and the droplet oscillation phenomena are analyzed. The numerical results are compared with the theoretical solution to clarify the sensitivity of the phase-field method to its hyper parameters such as the mobility and the interface width.