A numerical experiment of convection course driven by surface cooling in aquatics waters

Abstract:

Based on a numerical experiment carried out with a simple rectangular water area as an example, the paper discussed the developing progress of convection driven by surface cooling in aquatics waters with free surface quantitatively. In view of the common characteristics of velocity, depth and other given values in lake and other aquatic waters, the values of Re, Gr, Pr could be taken of 8000, 500000 and 10 respectively. The result shows that the convection driven by surface cooling could be subdivided into three phases, i.e. the occurring phase, the developing phase and the steady phase. The development of fields of the velocity and temperature at different phases is affected by rates of the effective potential energy distributed to the diffusing and heat transporting, with convectional eddies and isotherms being formed at the same time correspondingly. Big convectional eddies were brought out by the convection driven by surface cooling, with the magnitude of their diameters being equal to the depth at the end; the distribution of isotherms changed from horizontal form at the beginning to the vertical at the end, so that the water is exchanged fully from surface to the bottom.