Unsteady turbulent natural convection in a tank

This paper deals with an analytical and experimental study on unsteady turbulent natural convection in a tank which is subjected to a uniform lateral heat flux. Based on the solutions of the boundary layer equations at time T, the vertical temperature distribution in the tank fluid at time T + Delta-T, was obtained by use of tank circulation model originally proposed by Turner (1969). In the experiments, the range of the modified Grashof number was 1-10 Trillion, and the Prandtl number was 7. Measurements of the temperature field and flow visualizations by use of dye tracer were conducted. The major results obtained are: (1) at the latter stage of the convection, the boundary layer along the roughly lower half of the heated wall entrains the core fluid, while the upper half of the boundary layer discharges its own fluid into the core region; (2) after the early stage of the convection, the major part of the boundary layer fluid is discharged into the core region across the outer edge of the boundary layer; and (3) the temperature field predicted by the analysis, which includes the boundary layer discharge across its outer edge, was in good agreement with the experimental data.