Hydrodynamic characteristics of fine-mesh minnow netting for sampling nets

Fine-mesh minnow nettings with a high solidity ratio (defined as the ratio of the projected area to the total area enclosed by the outline area) of 0.44–0.72 were used to investigate the hydrodynamic characteristics for various angles of attack (0°–90°). A brief summary of knotless plane netting in an expanded solidity ratio range of 0.075–0.75 is given. Experimental results show that the drag coefficient of minnow netting in a solidity ratio range of 0.44–0.72 is 0.13 to 0.035 in the parallel case and 1.60 to 1.86 in the normal case. The dual effect of the solidity ratio on the drag coefficient of knotless plane netting is confirmed in a wider solidity-ratio range. The maximum lift coefficient of minnow netting increases from 0.55 to 1.02 for an angle of attack of 40° as the solidity ratio increases from 0.44 to 0.72. The proposed empirical formulas of the hydrodynamic model in terms of drag and lift coefficient for knotless plane netting varying a wider solidity ratio and angle of attack are more accurate than those of previous models. Therefore, the present formulas allow precise numerical calculation for the optimal design of sampling nets and fishing gear. •Drag coefficients ofminnow netting at solidity ratio range from 0.44 to 0.72 were 0.13 to 0.035 in parallel case, and 1.60 to 1.86 in normal case, respectively.•A dual effect of solidity ratio on the drag coefficient of netting was confirmed in a wider solidity-ratio range from 0.075 to 0.75.•The maximum lift coefficient of minnow netting increased from 0.55 to 1.02 as the solidity ratio rises up to 0.75 at the angle of attack of 40°.•The present empirical formulas of hydrodynamic model of knotless plane netting are more accurate than those of previous models.