Modelling aspects of two phase flow

In two phase flow scaling is much more limited to very narrowly defined physical phenomena than in single phase fluids. For complex and combined phenomena it can be achieved not by using dimensionless numbers alone but, in addition, a detailed mathematical description of the physical problem - usually in the form of a computer program must be available. The scaling of the thermodynamic data of the modelling fluid is important. From a literature survey and from own scaling experiments the conclusion can be drawn that Freon is a quite suitable modelling fluid for scaling steam - water mixtures. However, without a theoretical description of the phenomena, nondimensional numbers for scaling two phase flow must be handled very carefully. (author)