On the Form of Momentum Convection Term in the SPACE Multi-Dimensional Thermal- Hydraulic Module

For a realistic analysis of a LOCA, many system codes have been developed. These codes usually adopt a one-dimensional approach for the analysis of a two-phase flow and some of them have used a three-dimensional (3D) thermal-hydraulic module. However, the 3D two-phase flow modules still have great uncertainties in both physical models and numerical methods. Jeong et al. showed that the form of two-fluid momentum equations significantly effects on the results of calculations, especially for a strongly heterogeneous two-phase flow. The thermal-hydraulic safety analysis code, SPACE, also has a multi-dimensional thermal-hydraulic module. In this study, the semi-conservative form of momentum equations was implemented into the SPACE multi-dimensional module. For the DYNAS test, the results of the modified SPACE code showed the better agreement with the experimental data in general. In conclusion, the computational accuracy of the SPACE multi-dimensional module was greatly improved by modifying the form of the momentum convection term, especially when the two-phase flow is strongly heterogeneous.