Three-Dimensional Initiation of Thermohaline Fingering
This study involves a series of three-dimensional numerical simulations of the unstable fingering regime of thermohaline convection. We present two cases which demonstrate how the salt finger flow field development is dependent upon the density ratioR p In both density ratio cases, the initial stages of the flow field are wave dominated. In the lower density ratio caseR p =1.2, interfaces with jumps in salinity and temperature develop within the first period of the initial wave stage. Salt fingers form at these interfaces, while large scale convective motion in regions surrounding the interfaces contribute to the development of “staircase” temperature and salt profiles as observed in the ocean. The combined interaction between shear and fingering believed to generate persistent fingering is not observed and eventually the staircase pattern breaks down. For higher values of the density ratio(R P =2), sharp jumps in salinity develop with the formation of some fingers. However, the fingers ultimately begin to fill the computational domain and the wave behavior initially observed continues to dominate with no formation of staircase profiles. The behavior of the solution in both cases was found to be dependent upon the initial conditions and mesh resolution. In particular, the form of the initial conditions played a key role in producing the interfaces and the staircase salt and temperature profiles observed in the lower density ratio case.
KeywordsDirect Numerical Simulation Salinity Gradient Flux Ratio Buoyancy Flux Mesh Resolution
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