Effects of roll motion on air distribution and frictional resistance of an air-lubricated container ship

Air lubrication technology reduces ship frictional resistance by injecting air beneath the hull, yet how ship roll motion alters the near-wall air distribution and frictional resistance response remains poorly understood. This study uses full-scale unsteady Reynolds-averaged Navier–Stokes (URANS) simulations coupled with the volume-of-fluid (VOF) method and an overset grid to investigate prescribed roll motion of a 14,000 TEU container ship. Roll motion drives a cyclic transverse migration, lateral leakage, and recovery (TLR) process of the injected air beneath the hull. For the representative 5°, 0.025 Hz case, the time-averaged downstream air mass flow decreases from 5.18 to 4.17 kg/s, while the mean hull-bottom frictional resistance increases from 104 kN at ventilated even keel to 196 kN under roll and exhibits a relative fluctuation amplitude of 19.2%. The roll frequency mainly modifies the temporal development and fluctuation characteristics of the resistance response, whereas the maximum roll angle is the primary factor affecting the degradation of near-wall air distribution and the increase in time-averaged frictional resistance. Preliminary ship-specific correlations are provided for the prescribed roll range. These findings provide an engineering reference for assessing the sensitivity of air distribution and frictional resistance to representative roll conditions encountered in service.