LAUSR

Abstract Air lubrication by means of a bottom cavity is a promising way for ship drag reduction. The characteristics of air layer under the bottom cavity and effect of drag reduction are sensitive to the attitude of ship model. To investigate the stability of air layer under different navigation condition of air cavity ship, a method with the combination of RANS equations and VOF model is proposed for the viscous-flow calculation of a large flat bottom ship, which is verified by the model-test result. The effect of heeling and trim on the formation and stability of air layer is investigated. Present numerical results show that there is a critical value of heeling arctan ( h / B c ) with the definition the cavity depth and width of the h / B c . The air layer would be stable if ship heeling is less than the critical value. The air layer broke when the heeling is greater than the critical value, and heeling increase, broken phenomenon aggravate. The trim angle of the ship is unfavorable to the stability of the air layer and it should be avoided as much as possible in the course of navigation.