A Scale Effecat Evaluated by Drag Measurement Comparisons between Prototype Plane Nets and One-fifth Model Based on Tauti's Law

Abstract

To estimate the scale effect on the modeling of fishing nets, six prototypes andtwo models of plane nets were prepared in experiments. The ratio of the twine diameter between the model and the prototype satisfied Tauti's law of similarity. Drags of each net, which were mounted on a streamline frame, were measured in a flume tank. The measured drags of the prototype nets were compared with the drags converted from the measured drags of the model nets according to Tauti's law.
The results showed that the converted drags of the prototype nets were higher than the measured drags. These differences caused by the change of the drag coefficient can be expressed as a function of Reynolds number in Tauti's law. To correct the scale effect on the converted drag, the curve relating the drag coefficient, C_d, within the wide range of Reynolds number, R_e, C_d-R_e curves, should be confirmed by experiments for many kinds of net.