Flow visualization, transport mechanism and temperature distributions in an enclosure with two side walls each differentially heated: Upper half, cold; lower half, hot

Due to the experimental difficulties brought about by the high pressure and temperature growth conditions flow and heat transport in a hydrothermal autoclave for the growth of single quartz crystals has been studied mostly numerically. To date, most of the numerical models and associated results are not validated, or only qualitatively validated through results derived from crystal growth production. In this study, the authors used a simulated model reactor represented by an enclosure with the two lower half sidewalls uniformly heated while the upper halves are uniformly cooled. Flow in the reactor is qualitatively visualized using a full field flow lighting and seeding technique and quantitatively evaluated using particle image velocimetry. Finally, based on the physical setup and experimentally determined boundary conditions, flow is numerically simulated and compared to the experimental results. The agreement between the experimental and the numerical data was used to validate the numerical model. The ensuing parametric study shows the changing of flow pattern and velocity magnitudes for two differential temperature cases: (ΔT=10°C and ΔT=1°C) and a variety of enclosure aspect ratios.