The reduced-moderation water reactor (RMWR) core adopts a hexagonal tight-lattice arrangement with about 1mm gap between adjacent fuel rods. In the core, there is no sufficient information about the effects of the gap spacing and grid spacer configuration on the flow characteristics. Thus, we start to develop a predictable technology for thermalhydraulic performance of the RMWR core using an advanced numerical simulation technology. As a part of this technology development, we are developing an advanced interface tracking method to improve the conservation of volume of fluid.
The present paper describes a part of the verification works of the two-phase flow simulation code TPFIT. The numerical results applied to liquid film falling down on an inclined flat plate are shown and compared with existing experimental results. In the results of numerical simulation, the development of the wave structures could be reproduced by the numerical simulation. The predicted average local film thicknesses almost agreed with Nusselt's mean film thickness. Moreover, the probability density function of local film thickness agreed well with the experimental result. In addition, the trends related to the film velocities were consistent with the theoretical results. From these results, it was confirmed that the TPFIT code is applicable to predict the liquid film flow behavior.
