HEAT AND MASS-TRANSFER BY THE TURBULENT THERMOHALINE CONVECTION

The turbulent thermal and concentrational convection problem in a horizontal layer has been solved in the case Sc much greater than Pr greater than or similar to 1, i.e. when the salt molecular diffusion sublayer is deeply within the thermal molecular conductivity sublayer. This is the case for the subsurface sea water (Sc/Pr almost-equal-to 88), where the thermohaline convection is caused by the evaporation from the surface. The similarity considerations and an independent semi-empirical theory are used to derive relations for temperature and salinity profiles in different sublayers of the entire domain z greater-than-or-equal-to 0. The heat transfer law Nu = A(T)[Ra(T)(1 + B-1)]1/3 and the mass transfer law Sh = A(S)[Ra(S)(1 + 81PrB/16Sc)]1/3 are obtained from the relations for d(T)/dz and dsBAR/dz in the whole range of parameter B = alphaH/betaM values. The heat transfer relation is the same as for the moist convection, but the mass transfer relation differs from the moist convection case by the term 81Pr/16Sc. As \B\ --> infinity, the convection becomes purely thermal, and the salt can be considered as a passive admixture. On the contrary, as \B\ --> 0, the convection becomes purely haline, and the contribution of temperature fluctuations into buoyancy forces can be neglected. The obtained theoretical results are compared with laboratory data.