6 resultados para Moses, of Khoren, 5th cent.

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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An overview on the onset of thermocapillary oscillatory convection in a floating half zone is provided, and it is a typical subject in the microgravity sciences related to the space materials science, especially the floating zone processing, and also to the microgravity fluid physics. The main interests are focused around the process for onset of oscillatory thermocapillary convection, which is known also as the bifurcation transition from quasi-steady convection to oscillatory convection. The onset of oscillation depends on a set of critical parameters, such as the Marangoni number, Prandtl number, geometrical parameters, and heat transfer parameters. Recent studies show that, there exists the bifurcation transition from steady and axial symmetric convection to the steady and axial non-symmetric convection before the onset of oscillation in cases of small Prandtl number fluids and in cases of larger Prandtl number fluids of fat liquid bridge with small aspect ratio. The transition process is a strong non-linear process because the velocity deviation has the same order of magnitude as that of an average flow after the onset of oscillation, and unsteady 3-D numerical simulation is suitable to do in depth analysis on strong non-linear process, and leads generally to a better comparison with the experimental results.

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介绍了第五届国际流体力学会议(Proceedings of the 5th International Conference on Fluid Mechanics,2007年8月15~19日,上海)的基奉情况.大会报告涉及生物流体力学、湍流与流动控制、超声速流动、超空泡减阻、破碎波与海岸泥沙输运等当前流体力学前沿领域的研究进展;按流体力学学科分支总结了本次会议分会场交流论文的基本情况,阐述了若干学科分支方向的研究进展.……

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A temperature-controlled poolboiling (TCPB) device was developed to perform poolboiling heat transfer studies at both normal gravity and microgravity. A platinum wire of 60 μm in diameter and 30 mm in length was simultaneously used as heaters and thermometers. The heater resistance, and thus the heater temperature, was kept constant by a feedback circuit. The fluid was R113 at 0.1 Mpa and subcooled by 24 nominally for all cases. The results of the experiments at both normal gravity and microgravityin the Drop Tower Beijing were presented. Nucleate and two-mode transition boiling were observed. For nucleate boiling, the heat transfer was slightly enhanced, namely no more than 10% increase of the heat flux was obtained inmicrogravity, while the bubble pattern is dramatically altered by the variation of the acceleration. For two-mode transition boiling, about 20% decrease of the heat flux was obtained, although the part of film boiling was receded inmicrogravity. A scale analysis on the Marangoni convection surrounding bubble in the process of subcooled nucleate poolboiling was also presented. The characteristic velocity of the lateral motion and its observability were obtained approximately. The predictions consist with theexperimental observations.