Abstract
Accurate simulation of turbulent free surface flows around surface ships has a central role in the optimal design of such naval vessels. The flow problem to be simulated is rich in complexity and poses many modeling challenges because of the existence of breaking waves around the ship hull, and because of the interaction of the two-phase flow with the turbulent boundary layer. In this paper, our goal is to estimate the lift and drag coefficients for NACA 0012 of hydrofoil advancing in calm water under steady conditions with free surface and emerged NACA 0015. The commercial CFD software FLUENT version 14 is used for the computations in the present study. The calculated grid is established using the code computer GAMBIT 2.3.26.The shear stress k-ωSST model is used for turbulence modeling and the volume of fluid technique is employed to simulate the free-surface motion. In this computation, the second order upwind scheme is used for discretizing the convection terms in the momentum transport equations, the Modified HRIC scheme for VOF discretisation. The results obtained compare well with the experimental data.
Highlights
Since 1960s, Computational Fluid Dynamics (CFD) has made remarkable progress
From the pressure vectors along the hydrofoils, it can be observed that much larger adverse pressure occur on the pressure side of the NACA0015, this observation is confirmed by the results of pressure coefficient distribution along our profile, as shown in figure 3. a larger separation zone is observed near the trailing edge for the NACA0015 foil, as shown in figure 4 This steeper pressure gradient implies that more intense dynamics can be expected in the cavitating flow
Hybrid meshes reduce the number of cells whilst respecting the relatively tough constrains of the solver regarding their aspect ratio and skewness, A ¿ne meshing is applied near the free surface, The total 140000 cells are used for the computational domain
Summary
Since 1960s, Computational Fluid Dynamics (CFD) has made remarkable progress. The main impetus to this progress is the increasing industrial demands. Lots of model tests are required and it is costly and time consuming. Engineers turn to advanced numerical tools in aid of their engineering design. In ship industry, due to the existence of free surface and complex ship geometry, ship CFD has fallen behind the other industrial fields. With the recent breakthrough in ship CFD technology, practical applications of CFD in analysing and predicting ship performance become possible
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