Modelling Strategies and Two-Phase Flow Models

Abstract

We will recall first the general methods of solution of thermal-hydraulic problems and then show how these are complicated by the presence of multiphase flows before entering in the following sections into the descriptions of the various approaches. 2.1.1 General Methods of Solution The design and transient behaviour problems are treated in a similar manner. Starting from the general conservation laws: • conservation of mass • conservation of momentum • conservation of energy, we express these by partial differential equations. We choose the minimum required number of space variables and consider, if necessary, time dependence. Very often we deal with one-dimensional systems and with cross-sectionally averaged variables. We then "close" or complete the set of equations by including the necessary constitutive laws and relations, namely,