Numerical Simulations of a Bulk Carrier with Flettner Rotors Using a Fully Nonlinear Potential Flow Solver

In order to tackle emissions reduction and the decarbonization of the maritime industry, increasing effort is put into finding other means to propel a ship. In this respect, wind-assisted propulsion is becoming increasingly popular, with Flettner rotors being one of the preferred choices thanks to their simplicity and the possibility of retrofitting existing vessels. To obtain reliable predictions of the fuel-saving capabilities coming from the use of the rotors, it is important to carry out numerical simulations considering realistic scenarios. For this aim, in this paper, a fully nonlinear unsteady potential flow method is employed to simulate free sailing conditions. Ad-hoc simplified models are implemented to mimic propeller and rudder actions. To address viscous effects affecting free sailing, virtual captive tests have been performed with a viscous solver and the manoeuvring coefficients are added to the equations of motion of the potential flow method. A simplified model for the wind and for Flettner rotors is also included in the solver. Results from simulations of a bulk carrier in calm water under different wind conditions are presented.