Observations on Some General Aspects of Modelling Methodology

Observations on Some General Aspects of Modelling Methodology 

Concerning the entities defined above (each entity together with its attributes) we introduce here the notion of basic devices with various types of connections. 

One of the characteristics of basic devices is that they cannot be split up into parts. A basic device can also be a signal transformer (a function tvhich transforms the input into output, such as the thermocouple that transforms the input temperature into an electrical tension). The process phases are connected and characterized quantitatively, from the vievrpoint of characteristic relations (equations), as in Fig. 1.4 [1.11-1.13]. This structured mathematical modelling development corre- 

Various laws restrict the values of the process quantities. These laws may represent either fundamental, empirical physicochemical relationships or experimentally identified equations (from statistical modelling or from dimensional analysis particularizations). In contrast to statistical or dimensional analysis based models [1.14], which are used to fix the behaviour of signal transformers, the models of transport phenomena are used to represent generalized phases and elementary phase connections. Here, the model equations reveal all the characterizing attributes given in the description of a structure. They include balance equations, constitutive equations and constraints. 

---