Ship Emission Reduction via Energy-Saving Formation

The importance of Maritime transportation energy conservation and emission reduction has been increasingly recognized. A novel bio-inspired method utilizing the favorable hydrodynamic interaction in ship convoys is introduced in this paper to achieve an energy bonus for the whole formation system or/and the members. Firstly, grid convergence analysis and virtual captive model tests are conducted to verify the grid discretization method and validate the adopted numerical method. Following this, simulations based on STAR CCM+ are performed in different configurations at low speeds ( $Fr = 0.0479 \sim 0.0958$ ) to reveal how sailing in formation affects energy consumption. Then, the speed effects on ship convoy resistance are investigated with two specific speeds ( $Fr=0.0958, 0.2$ ). A generalized model based on support vector regression (SVR) is established to evaluate the resistance characteristics of ships in different layouts and velocities to find the optimal configuration for ships in different scenarios. Furthermore, the computational fluid dynamics (CFD) results of model-scale ships, based on the VOF (Volume of Fluid) method, are extrapolated to full-scale ships. The results show that the fuel savings and emission reduction could reach up to 5.09 $\%$ at $Fr$ =0.2 when the longitudinal distance between the ships equals to 1.125 of the ship length. The conclusions of this work could provide theoretical support for utilizing the bonus of sailing in formation.