Abstract: A method is provided for reducing skin-friction of a ship moving through bubbly flow fields generated in proximity of hull surfaces by jetting gas through a plurality of jet nozzles provided on hull surfaces of the ship. The gas flow rate is controlled so as to establish a peak void fraction in a turbulent boundary layer, by applying an observation that the location of a peak void fraction shifts away in a direction normal to the hull surface with increasing gas flow rate through the jet nozzles.

Abstract: Distribution pattern of bubbles produced from a bubble jet of a ship is analyzed by approximating the bubbly flow as a continuous flow of a gas phase and treating the bubbles as diffusing particles dispersing in a flow of the gas phase.

Abstract: A method for reducing the frictional resistance of a navigating vehicle, and a method for generating micro-bubbles for reducing the friction of the navigating vehicle and an apparatus therefor. The friction reduction is achieved with the expenditure of a small amount of energy, thereby improving the overall energy efficiency for operating the ship. An air bubble/water mixture is injected towards the stern of the ship, at an inclined angle to the underwater surface, into a boundary layer formed in the vicinity of the underwater surface of the ship. The friction reduction is effectively performed because of the dynamic energy of the water, being a larger mass than air, enables the gas-including mixture to be injected over a longer distance into the boundary layer than in the case of air bubbles alone.