Experimental investigation and analysis of hydrodynamic characteristics of a net panel oscillating in water

To investigate the behaviour and hydrodynamic characteristics of supple nets in a wave, experiments of forced oscillation were conducted in a tank with square net panels. The four corners of the net panel were fixed to the oscillation device with a specific pretension. The hydrodynamic loads acting on the corners of the netting were measured. To simulate the experiments, a numerical model based on dynamic finite element analysis was constructed. Comparing the amplitude and phase of measured loads with the calculated results, the drag coefficient Cd and inertia coefficient Cm were determined by interpolation and iteration. The effects of various parameters on Cd and Cm were investigated. The results show that: (1) drag force is dominant at low frequency, whereas the contribution of inertia force increases with an increase of the Keulegan–Carpenter number or frequency; (2) with increasing frequency, both Cd and Cm show a decreasing trend, and the trend of Cd against the Reynolds number is similar to that in steady flow; (3) increasing oscillation amplitude makes Cd decrease, but it has no significant effect on Cm; (4) solidity generally has a positive effect on Cd and Cm.

► A special experiment of forced oscillation with fishery net panel is designed. ► Drag force is dominant at low oscillation frequency. ► The contribution of inertia force increases with increasing Kc number or frequency. ► The trend of Cd against the Reynolds number in waves is similar to that in steady flow. ► Increasing amplitude makes Cd decrease, but it has no significant effect on Cm.