Abstract
An experimental work is performed to examine the characteristics of internal fluctuations in two-layer thermal strata induced by the combined action of grid-oscillation and heating from below. The interfacial layer depth and the vertical deformation of interface are expressed as a function of Péclet number and the overall Richardson number which are defined from the grid-turbulence scaling velocity. Based on these results, it is found that the relative intensity of temperature fluctuationn at the thermocline is proportional to Péclet number as well as to the inverse of Richardson number. It is concluded that the mechanical turbulence plays more predominant roles on the internal fluctuations than the thermal convection. However, the thermal stirring effectively contributes to the mixing process because of its buoyancy flux effects.
