EVALUATION OF SCALE EFFECTS IN HYDRAULIC MODELS BY ANALYSIS OF LAMINAR AND TURBULENT FLOWS

The paper presents an analysis of laminar and turbulent flow in porous stone material to evaluate the order of magnitude of scale effects in hydraulic models. Hydraulic model tests, such as for example breakwater model tests, are normally carried out at such small scales that the flow through the various layers of the breakwater is not completely turbulent. A well-known method to compensate for the scale effects is to use larger stones than calculated by Frude's model law in certain regions of the model. The paper presents formulae for calculating the compensated stone sizes. An evaluation of the energy dissipation in hydraulic models is made in order to determine the scale effect due to 'laminar' flow.