Development of Computational Method for Calculating Ship Viscous Flow at Full-Scale Reynolds Number

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Ship designs in next generation will be dramatically different from those currently in use. As such, more innovative design concepts will be applied for design of ships with higher performance and overall operation benefit. In the design of such hull forms, much of the current design database, which has been developed over the past 50 years is not directly applicable. Since it will be prohibitively expensive to quickly expand the design database through model studies, there is strong motivation to develop simulation-based design tools, which are able to diminish or eliminate need for model-scale tests and extrapolation of the results to full scale. This is an important background of further development of Computational Fluid Dynamics (CFD) ; however many CFD methods especially for those based on Reynolds-averaged Navier-Stokes (RaNS) equation method, still suffer difficulties in full-scale ship-flow simulation.The present study concerns development of computational method for simulation of ship viscous flow at full-scale Rn in conjunction with consideration of near-wall flow modeling including surface roughness effects. The main objectives are two folds : (1) development of RaNS equation method applicable to full-scale flow simulation; and (2) investigation on appropriate physical model for full-scale Rn. In particular, the validity and advantage of two-point wall-function approach^<3)> has been investigated and extended for inclusion of surface roughness effects on flow and resistance. The present numerical method for Mi-scale ship-flow simulation is based on extension of method developed by the present investigators, such that, in association with standard κ-ε model, two near-wall models can be employed, i. e., two-layer method and two-point wall-function method with capability to include surface roughness effects, where the latter has been shown more suitable in practical design use.