Numerical simulation of air cavity under a simplified model-scale hull form

Abstract

Injecting air under hulls of marine vessels can lead to reduction of their hydrodynamic resistance. Since experimental development of air-assisted hulls usually requires a large number of tests, numerical simulations of air-ventilated water flows can potentially accelerate the design process. In this study, computational modeling has been carried out for the previously tested simplified hull form with an air cavity formed behind a step. To achieve proper agreement with experimental results, it is established that a sufficiently fine numerical mesh needs to be generated at the cavity re-attachment to the hull and the sharpening treatment of the air-water interface must be included. It is also shown how the cavity length can be manipulated by changing inclination of the cavity-originating step. Keywords: Drag reduction, Air-cavity hull, Two-phase flow, Computational fluid dynamics, Validation and verification