Multibody Simulation for Gravity-Driven Falling Film Using Computational Fluid Dynamics

Abstract

The annular flow two-phase regime appears in nuclear power plants cooling by water. On accidents with lost of cooling this regime determine the heat extraction conditions from the core. The experimental facility Gerador de Película Ondulatoria (GEPELON) was constructed at Universitat Politècnica de València to study this phenomenon. In this work, we use computational fluid dynamics techniques to simulate an air-water regime, specifically a gravity-driven falling liquid film in the GEPELON experimental facility. We consider a multibody geometry where the porous sintered of the input device is simulated in a realistic way. The Volume of Fluid (VOF) model was used in the resolution of the constitutive equations. We propose three geometric approximations to estimate film thickness, and simulation results were compared with experimental values. The simulation results show a good agreement with experimental measurements. Besides, no significant differences were observed between geometrical approximations for film thickness calculations.

Experimental measurements and CFD results of liquid film thickness in vertical downward air–water annular flow

“…However, there is a diffuse zone that occupies multiple cells where the volume fraction goes from 1 to 0 and where the interface is located. There are different methods to approach this problem [32] although for this analysis it has been decided to simply locate the interface at the coordinates where the volume fraction is equal to 0.5. In the future, it is expected to obtain the percentage of space in the cell occupied by the liquid and to collapse all the volumes into a single liquid film.…”