Anomalies in One-Dimensional Thermal Hydraulics Calculations

Abstract

Thermal hydraulics calculations, especially those based on two-fluid models, can sometimes exhibit peculiar anomalies which are very difficult to diagnose. Several such anomalies are discussed below. In particular it is pointed out that: 1. in HEM calculations computed hydrostatic equilibria will not be unique unless the final temperature distribution is fixed in someway; 2. that even very plausible difference approximations may preclude the possibility of achieving hydrostatic equilibrium in two-fluid calculations ;3. and that, in two-fluid calculations, computational results may be extremely sensitive to even small details of the interphase-drag model.Reasons for, and characteristics of such anomalies are discussed in some detail.