A preliminary method for the numerical prediction of the behavior of air bubbles in the design of air cavity ships

Abstract

Air-cavity ships (ACS) are advanced marine vehicles that use air injection under hull to improve the vessel’s hydrodynamic characteristics. Although the concept of drag reduction by supplying gas under the ship’s bottom was proposed in the 19th century by Froude and Laval, at this time there are not many systematic studies on this subject. This paper is a preliminary work with the purpose of being a basic tool for the design of the ACS with computational fluid dynamic methods. The study aims to conduct a series of computational tests to compare the numerical models of bubble with experimental data. The first step of this study was to investigate the behavior of free bubble in water, considering as parameters the critical mass of air, the rising speed and aspect ratio of the bubble. Then it is evaluated the interaction bubble-flat plate in order to obtain a reliable prediction of the behavior of air bubbles under the hull.