Pages 173-178
This paper describes experiments on the mixing of stratified fluid by=surface cooling. A small tank is filled with water with a constant=temperature gradient in depth and cooled at the top copper plate by=circulating cool water of a constant temperature. The two-dimensional=primary flow is visualized using fluorescence dye and analysed by the=digital image processing. The temperature fluctuation is measured using a=platinum resistance wire. Soon after the cooling starts, a thin layer beneath the cooled top plate=becomes unstable so as to make periodic lateral fluctuation visible. The=periodic mass concentration due to this instability leads to the formation=of regular flow structure with a raw of drops of dense water. While=falling down, these drops grow into blobs by entrainment of ambient fluid. =It is confirmed that although the interaction of the blobs with each other=such as coalescence, merging and absorption seems to be chaotic, the depth=of the mixed layer increases at the rate proportional to the root of time. =These experimental results are consistent with the computational results of=the two-dimensional flow structure reported in the preceding paper. It is=concluded that the two-dimensional features of the mixing by surface=cooling are simulated in a successful manner in the experiment and in the=computation.
