Harmonic wave and steady current effects on plane fish nets

Individual and interaction effects of parallel current and waves on three plane nets were empirically examined. A current opposing the direction of the waves was shown to shorten the wavelength while a current in-line with the direction of the waves stretched the wave length. Due to these wave modifications, the combined loads produced by a current and waves were significantly less than the sum of current and wave forces applied individually. Applying a vector approach, the unsteady loads were split into drag forces and inertia components. Both components contributed considerably to the hydrodynamic loads for wave-only cases. For combinations of waves and current, the inertia force was significantly greater than the drag force. Further insights were also provided into the concepts of effective thickness and the modified Keulegan-Carpenter number as parameters quantifying inertia force and drag force for fishnets.