TED-AJ03-576 CONVECTIVE INSTABILITIES INDUCED IN A CRITICAL FLUID

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概要

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• As the fluid system approaches the critical point, physical properties such as the specific heat and the isothermal compressibility diverge. Because of the large specific heat, the thermal diffusivity is very low, which suggests that thermal energy cannot be transferred quickly by thermal diffusion or heat conduction in critical fluids. It had been supposed that the temperature propagation speed is very low in critical fluids under microgravity conditions because of the reduction of both heat conduction and buoyancy convection. However, it was discovered that temperature propagates very quickly in critical fluids. Now, it is known that temperature propagates as acoustic waves in critical fluids, which is named the piston effect. Convection induced in critical fluids under terrestrial gravity conditions has also been investigated both numerically and experimentally. Since the temperature coefficient of volume expansion is very large and the thermal diffusivity is very low in critical fluids, strong buoyancy convection may be induced due to the very high Rayleigh number. The Prandtl number is also very large due to the very low thermal diffusivity, which may cause a different type of convective instability. The convective characteristics in critical fluids, however, have not yet been well understood. In this paper , we study thermal convection induced in a critical fluid under terrestrial gravity conditions theoretically and numerically. In the second section, we explain the experimental result concerning thermal convection induced in critical CO_2. In the third section, we analyse the onset of thermal convection and the convective features both theoretically and numerically. In the final section, we summarise the results, which we obtained in this study. Wefind that power laws apply to the onset times and wavenumbers of thermal convection in terms of the system temperature deviation from the critical temperature and that the powers are expressed by the critical exponents of some physical properties.

• 一般社団法人日本機械学会の論文

著者

• Maekawa Toru

  Toyo University

• SHIROISHI Yoshinori

  Toyo University

• ISHII Koji

  Osaka Prefecture University

• AZUMA Hisao

  Osaka Prefecture University

• YOSHIHARA Shoichi

  National Aerospace Laboratory of Japan

• OHNISHI Mitsuru

  National Aerospace Laboratory of Japan

• Yoshihara S

  Toyo University

関連論文

• TED-AJ03-576 CONVECTIVE INSTABILITIES INDUCED IN A CRITICAL FLUID
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• Instability of Thermomagnetic Convection under Microgravity -Dropshaft experiment and linear stability analysis-
• Molecular Dynamics Analysis of Thermal Energy Transfer in Supercritical Xenon
• Crystal growth of an InAs-GaAs binary semiconductor by the Travelling Liquidus Zone Method

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