A SCALE EFFECT EVALUATED BY DRAG MEASUREMENT COMPARISONS BETWEEN PROTOTYPE PLANE NETS AND ONE-5TH MODEL-BASED ON TAUTIS LAW

To estimate the scale effect on the modeling of fishing nets, six prot otypes and two models of plane nets were prepared in experiments. The ratio of the twine diameter between the model and the proto-type satis fied Tauti's law of similarity. Drags of each net, which were mounted on a streamline frame, were measured in a flume tank. The measured dra gs of the prototype nets were compared with the drags converted from t he measured drags of the model nets according to Tauti's law. The resu lts 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 c urve relating the drag coefficient, C-d, within the wide range of Reyn olds number, R(e), C-d-R(e) curves, Should be confirmed by experiments for many kinds of net.