NUMERICAL SIMULATIONS OF WAVE COLLAPSE PHENOMENA NEAR BOWS OF HIGH SPEED SHIPS

초록

Recently, the estimation of wave resistance on high speed ship becomes significantly important as the speed increases in accordance with the trend of fast and safe modern ship navigation. The occurrence of wave collapse or spray near the bow of a high speed ship and its prediction plays an important role in evaluating the whole ship resistance effectively. The wave collapse phenomena through numerical simulations have been performed in this paper for the purpose of analyzing the characteristics of the wave resistance acting on ships at different ship speeds and bow shapes. Present research investigates the numerical simulation methods for wave collapse phenomena near bows of high speed ships. The numerical simulation method developed in this research includes three dimensional effects as well as nonlinear free-surface conditions in investigating the wave breakings accompanied by the wave collapse. Navier-Stokes equations are differentiated based on finite difference method, and Marker-density scheme is used for the description of the complex free-surface more realistically by replacing the ordinary free-surface conditions, associated with the differentiated governing equations. In the Marker-density scheme, the air-water interface or the free-surface is treated applying the marker density. Fixed staggered rectangular mesh is used as grid system. And Cartesian Cut Cell scheme is applied for the accurate geometry definition in rectangular grid system. The simulation results are compared with experimental results and other calculation results. The agreements are good qualitatively. In addition, the effect of waves on a stationary model ship is simulated to check the possibility of green water simulation.