Detailed modelling of two phase flow and its application to system prediction

Following a brief discussion of the deficiencies of the widely used empirical modelling methods, the development of more phenomenologically based models is discussed in the particular context of the prediction of gas-liquid flows. The example of droplet deposition models is used to illustrate how a whole variety of phenomenological models can be developed to explain the same data. It is shown how the development of modern techniques for drop size and drop motion measurement may be used to throw more detailed light on the physical mechanisms. The next area explored is that of interfacial phenomena in two phase flow, with particular reference to wave behaviour and its link to shear stress in annular flow. Finally, a range of examples are given of the applications of phenomenological modelling, these applications being selected where possible to link closely with the general papers being presented in this session. The examples include flows in ''singularities'' (venturis, nozzles) and flows in diabatic systems with departure from thermodynamic equilibrium