Numerical Simulation of Current Generation in Deep Water Basin

With the increased activities in the exploration and production in oil and gas in 1,000–3,000m water depth, the offshore industry enters a challenging phase. Reliable model testing in deep water basins requires the controlled modeling of current and wave in time and space to achieve a well-defined offshore environment. Current generation is considered to be one of the key challenges for the design and construction of a physical deep water test basin. Apart from the physical setup, a virtual numerical wave basin is an integral part of the whole facility. Among others, accurate representation of current generation is an indispensable component of the numerical package in order to achieve an accurate numerical simulation of wave and current. In OpenFOAM, the density is not considered in turbulence formulations for two phase flow (Jacobsen, 2012 and Harrif, 2013) where free surface is considered. Thus excessive diffusion of turbulence takes place over the interface, which results in poor results of velocity profiles and turbulence quantities for current generation. In this paper, standard k–ε, realizable k– and SST k–ω turbulence models have been correctly formulated by taking into account the effect of density according to the references (Jones and Launder, 1972; Shih et al., 1994; Hellsten, 1997) and implemented in OpenFOAM two phase flow solver. The velocity profile and turbulence quantities have been calculated and validated against the data by Klopman (1994) using the modified turbulence models. The validation reveals that correctly formulated k–ε, realizable k–ε and SST k ω turbulence models yield better agreement, as compared to the existing models in OpenFOAM, with experimental data in terms of current profile and turbulence quantities. The numerical model is then applied to simulate the generation of a three-layer current system. The turbulence intensity and shear velocity profile are presented.