A true double-body method based on porous media model for simulation and froude scaling verification of an aquaculture vessel resistance

Abstract

A blueprint of a novel aquaculture vessel composed of rectangular cylinders, pontoons, and nets with the capacity for self-propulsion was drawn. However, when completely different flow features are caused by non-stream shapes, resistance prediction cannot be accurately performed through conventional ship model experiments as the existing scale rules may be invalid. Besides, the existence of nets creates obstacles not only in model tests but also in numerical simulations. Therefore, resistance evaluation of the vessel with nets is very challenging. Porous media model for nets is one of feasible solutions and was validated by previously published experimental results, although a control volume was required. However, porous media model is incompatible with volume of fluid multiphase, which makes the double-body method adopted inevitably. A literally true double-body method based on porous media model was proposed. The comparison of vessels with and without a net exhibited a beneficial interaction between the net and the vessel hull, especially for nets with higher solidity. Furthermore, the Froude scaling law was adopted based on the hypothesis of Reynolds number invariance. All the full-scale resistances predicted by it in seven scale ratios demonstrated satisfactory consistency, and the relative errors grew with the increase of the scale ratios.