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Description
Air lubrication involves the injection of air beneath a ship’s hull, either as a continuous air layer
(ALDR) or in the form of microbubbles (BDR), to reduce skin-friction drag and thereby improve
the energy efficiency of marine vessels. Though previous computational fluid dynamics (CFD)
investigations have predominantly focused on model-scale vessels or flat-plate geometries, their
boundary-layer characteristics differ from those of full-scale ships. This study therefore investigates
air lubrication on a full-scale ship and demonstrates reductions in both viscous and pressure
resistance. Two numerical approaches were evaluated: the Volume of Fluid (VoF) method and the
Euler–Euler method. The VoF approach was unable to reproduce the experimentally observed
dependence of shear-stress reduction on variations in the injected air volume. Furthermore,
simulations using a morphology-adaptive solver suggest that conventional Euler–Euler approaches
may be inaccurate in the ALDR regime. In particular, a more homogeneous distribution of air
beneath the hull than that predicted by the conventional Euler–Euler model should be expected,
with elevated dynamic pressure in the midship region driving the air toward the sides of the vessel.
Moreover, the shear-stress resistance predicted by the Euler–Euler approach persists along the
bottom of the vessel, which is inconsistent with previously reported experimental observations.
| Topic Area | Advanced Computational Methods and Applications in Marine, Subsea and Offshore Technology |
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