ABSTRACT
Dimensional analysis provides some basic information about the investigated phenomenon on the assumption that it can be expressed by a dimensionally correct equation containing the variables influencing it. Obtaining a certain grouping of variables allows, for example, a wider application and interpretation of experimental results. In hydraulics, the relationship between variables, any one of which may be dependent on the others, is usually experimentally investigated using a physical model. Expressing the parameter in physical dimensions also permits safe transformation from one system of units to another. Research on physical models is based on the theory of similarity between the model and prototype. This theory provides guidance on the preparation of experiments, computation of model parameters, processing of results, limits of their validity and likely scale effects. In the theory of similarity, a dimensionless number is usually regarded as a physically meaningful ratio of parameters that is dimensionless.
