Parameter optimization of a rectangular cambered otter board using response surface method

Otter boards are important device that provide a desired horizontal opening of a mid-water trawl net. High lift coefficients are essential for an otter board to maintain favorable fishing efficiency, especially for fishing target like Antarctic krill (Euphausia superba) which is often found in layers very close to the sea surface. Response surface method (RSM) was used to optimize the parameters of a rectangular cambered otter board in this study. The aspect ratio (0.8–2.0), maximum relative camber (2%–18%), and maximum camber position (10%–50%) were adopted as the independent variables. Hydrodynamic performances of twenty otter board models were simulated using numerical simulation. Results showed that RSM was applicable to describe the relationship between the selected variables and the maximum lift coefficient. The maximum lift coefficient was significantly affected by these three variables. An optimal otter was extracted in the optimal solutions, and the optimal parameters of aspect ratio, maximum relative camber and maximum camber position were 2.0, 15.5% and 35.1%, respectively. Under the optimal conditions, the maximum lift coefficient was improved by 20.5% compared with the initial otter board. The relative error differed by only 1.6% from RSM model predictions, which indicated the availability of the model experimentally.