Numerical Simulation of Bilge Keels Dimensions Effect on Stream Characteristics of Ship Roll Motion in Viscous Fluid

In this paper, hull ship with dome and different sizes of bilge keels has been simulated. Roll motion of ship hull DMTB-5415 model with or without the presence of forward speed for specifying the pressure and hydrodynamic moment distribution on hull surface has been studied. The time histories of the roll angle of ship hull are shown for stationary and moving ship. The Numerical results have been validated with experimental measurements in good agreement. This simulation is done by Ansys-Fluent with free-surface random vortex method and slender body theory. The Pressure and hydrodynamic moment decrease with the increase of bilge keels surface. The pressure distribution on bilge keels surface in longitudinal coordinate for stationary ship is nearly uniform. The imposed pressure on bilge keels intensifies with the increase of its surfaces area and the time histories of the hydrodynamic normal forces acting on hull surface for four different bilge keels sizes are shown. The imposed pressure on bilge keels intensifies with the increase of ship forward speed but the pressure difference acting on the upper and lower surface of bilge keels decrease then imposed hydrodynamic moment on hull surface and roll angle oscillation amplitude of hull decrease