Regularization of Two-Phase Flow Models

This paper illustrates the dominant role that numerical damping plays in the regularization of the two-phase flow models used in the RELAP5 and CATHARE codes. Dispersion analysis for a practical range of wave-number is used to examine the stability characteristics of both differential and numerical implementations of the two models. In this study it was found that numerical damping overshadows the effect of differential terms when they were added specifically to achieve a well-posed differential model such as is done for some flow regimes in the CATHARE code. Furthermore the added terms can result in non-physical dynamic behavior of the model.