ABSTRACT
The preceding chapters have explored various aspects of hydraulics. In each case a fundamental concept has been described and, where possible, that concept has been translated into an algebraic expression which has then been used as the basis of a mathematical model. Mathematical models are functions which represent the behaviour of a physical system, and which can be solved on a computer or calculator. A mathematical model is very convenient, since it is available whenever the engineer needs to use it. However, it may have occurred to the reader that some problems could be so complex that no adequate mathematical model could be formulated. If such a problem is encountered, what is the engineer to do? To deal with such problems it is necessary to find an alternative to mathematical models. One alternative which is frequently adopted is the use of scale model experiments. However, this approach also raises questions. For example, even when the experimental results have been obtained, there may be no self-evident (e.g. geometrical) relationship between the model behaviour and the behaviour of the full scale prototype. Thus, if an engineer wishes to employ model tests, two problems must be faced:
To this end it is necessary to identify physical laws which apply equally to the behaviour of model and prototype. Our understanding of such laws has developed progressively over the last century or so.
