CFD Analysis of Aerodynamic Thrust from Flettner Rotors on Feeder Ships Operating in Low-Wind Tropical Regimes: A Case Study for Maluku Waters, Indonesia

The maritime shipping industry faces urgent decarbonization mandates from the International Maritime Organization, driving interest in wind-assisted propulsion technologies. Flettner rotors, leveraging the Magnus effect, offer promising supplementary thrust but remain understudied in low-wind tropical regimes. This study presents a three-dimensional Computational Fluid Dynamics analysis of a Flettner rotor applied to a feeder vessel operating in Maluku Waters, Indonesia, where dominant wind speeds range 3–6 m/s. Steady Reynolds-Averaged Navier-Stokes simulations employing the k–ω SST turbulence model with low-Reynolds wall treatment (y⁺ < 1) were conducted for a rotor configuration featuring diameter D = 4 m, height L = 24 m (aspect ratio = 6), 1.2D end-plates, and constant rotational speed 200 rpm under beam seas conditions (90° apparent wind angle). Results demonstrate that the lift coefficient decreases non-linearly from 9.24 at 3 m/s to 6.41 at 6 m/s, while the drag coefficient declines from 3.87 to 2.68, maintaining a stable aerodynamic efficiency ratio (C_L/C_D) of 2.38–2.41. Effective thrust ranges from 15.8 to 49.2 kN after accounting for hull-rotor interaction losses. For a reference 60 m feeder vessel operating at 11 knots, this corresponds to main engine power reduction of 9.3%–29.1%, equivalent to 124–388 L/day marine diesel oil savings and 96–313 t/yr CO₂ mitigation per rotor. The findings confirm that Flettner rotors retain substantial thrust-generating capability in low-wind tropical conditions, supporting green shipping initiatives for Indonesia's eastern maritime logistics network and providing a validated numerical framework for region-specific decarbonization strategies.