No abstract

The dynamics of relaxation and transformation of the structure of convective flows of a weakly stratified liquid are investigated by optical methods in the case of uniform lateral heating. The experiments were carried out for different (small (S = 0.22%) and high (6.5%) basic-salinity values, for which the main parameters of the medium (the thermal expansion coefficient, the saline compression coefficient, the kinematic viscosity, the thermal diffusivity, and the salt diffusion coefficient) differ somewhat. It is shown that the dependence of the structure parameters on the properties of the medium is weak, which justifies the possibility of extrapolating the data of bench experiments on highly stratified liquids to weakly stratified natural systems, such as the atmosphere and the hydrosphere. It is shown that, over a wide range of the experimental parameters, the length and height of the convective cells vary at a constant rate.

The transformation of the structure of the density, optical refractive index, temperature, and salinity fields in the regimes of formation and disintegration of convection flows under uniform sidewall cooling of a continuously stratified fluid is investigated using optical and probe techniques. Although the height of the individual cells is almost constant in the various stages of the process, the field patterns change significantly. In the formation stage the contributions of the temperature and salinity to the density distribution compensate each other, the density profile is smooth and the optical refractive index profile is stepped. In the disintegration stage the density profile also becomes stepped. At large times a new convection flow is formed on the external boundaries of the cells due to the temperature difference between the cooled inner fluid and the warmer outer (undisturbed) fluid, and this flow maintains the structure contrast as the motion degenerates.