Since there is an obvious vapor-liquid interface in the pressurizer, the simulation is based on RANS equation of VOF multiphase flow model. When doing VOF multiphase flow transient calculations, the time step selection is based on Global Courant Number. Finally, two time steps of 1ms and 5ms are selected, and Global Courant Number of each time step is below 2, which can completely satisfy the requirements of the simulation calculation [19]. Realizable k-Turbulence Model can eliminate the negative positive stress of Standard k-which may appear when the average strain rate is especially large by correlating the coefficient of turbulent dynamic viscosity formula and strain rate. Compared to the Standard k-, Realizable kcan accurately predict the diffusion of planar and circular jets, and it has a good simulation effect for the flow in the pipeline, flow separation, free flow of mixed flow, and the secondary flow [20,21], so it was selected to deal with the turbulent flow of liquid phase. The finite volume method (FVM) is used to establish the solving control equation and the commercial CFD code ANSYS FLUENT is employed to solve the Reynolds-averaged Navier-Stokes equations with the Realizable k-turbulence model. The focus of this study is not on the fluctuation of the vapor-liquid interface. Therefore, in order to save computing cost, the free liquid surface reconstruction adopts modified HRIC format. In addition, the PISO algorithm deals with the coupling of pressure and velocity, and the QUICK scheme was used to discrete each control equation.

### Language ###
English

### Assessment ###
We can ask about the specific time steps mentioned in the simulation setup

### Query ###
What are the time steps used in pressurizer vapor-liquid interface simulations?
What are the time steps used in pressurizer vapor-liquid interface simulations?