J055014 密度成層中を運動する層流熱ブルームの温度場・組成場・速度場の同時可視化

Abstract

Fluid dynamics of thermo-chemical plumes in viscous fluids was investigated. Flow pattern, temperature and compositional fields were quantitatively visualized by microcapsules of thermo chromic liquid crystals, fluorescent dye, and a laser light sheet. The behavior of thermo-chemical plumes depends on the initial buoyancy ratio B_0, which is the ratio of the stabilizing chemical buoyancy to the destabilizing thermal buoyancy at the onset of convection, and also on time. For intermediate B_0, the interplay between the thermal and compositional effects generates complicated behaviors. Because all hot plumes cool by thermal diffusion as they rise, a chemically composite thermal plume eventually attain a level of neutral buoyancy, and a secondary plume is generated from the tip of the chemical dome, then at which it begins to collapse. The thermo-chemical blob is refueled after the falling process because heat flux of the heater is constant in our experiment. Here we describe the oscillation behavior of the thermo-chemical plumes for the intermediate B_o based on the results of the heat flux by the thermo-chemical plumes.