Abstract:
The analyses of turbulent flow around the ship hulls which includeWigley hull, Kriso container ship (KCS), Series 60, HSVA tanker and a catamaran hull are conducted for various Froude numbers using a commercial computational fluid dynamics (CFD) code STAR-CCM+. The finite volume method (FVM) is employed to discretize the governing equations of fluid flow and the SIMPLE (semi-implicit method for pressure linked equations) algorithm is applied to get the solution of pressure-velocity coupling equations. The k- turbulence model is chosen to give the closure to the Reynolds Averaged Navier Stokes (RANS) equations and the volume of fluid (VOF) method is applied to capture the interface between the two phases. Dynamic fluid body interaction (DFBI) module is used to simulate the motion of rigid body (ship hull) which is unconstrained to sink and trim. A trimmed cell mesher technique is used to produce hexahedral cell and prism layer mesher model is applied to resolve the turbulent flow accurately near the solid wall of the hulls.
The present numerical results (wave profile, wave pattern and resistance) obtained from STAR CMM+ for each mono hull are compared with those of its available experimental results and the agreement is found to be quite satisfactory. The sinkage and trim are calculated only for Wigley and KCS hull and are compared with the experiment. The predicted wave pattern is composed of transverse and diverging waves and looks very similar to Kelvin wave pattern. Moreover, the grid dependency study is carried out for Wigley, KCS and Series 60 hulls and as expected the finer are the grids, the better is the accuracy found with a cost of longer computation time.
In case of catamaran, the wave-making resistance of the catamaran hull exhibits broadly similar trends to those of the published monohull results as well as the experiment. However, the magnitude of the wave elevation of the inner side of the catamaran hull is slightly higher than that of the outer side at the first crest of the bow. This difference is mainly due to the wave-interference effects.
Above all, the standard two-equation k- turbulence model with near-wall function is used to predict the turbulent flow characteristics which are very close to experimental results and could be considered as a powerful tool for analyzing the viscous fluid flow.
