熱流束振動を加えた矩形容器内熱対流場の内部重力波共鳴 : アスペクト比の影響(熱工学,内燃機関,動力など)

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In this paper the thermal convection field and its resonance phenomena in a rectangular cavity with heat-flux vibration were numerically examined and the results were compared with the ones of square cavity. In the case of the aspect ratio α=5 and the Prandtl number Pr=0.71, for a range of the Rayleigh number Ra the critical angular velocity ω_c, at which the relative amplitude of midplane Nusselt number α_m has a local maximum, agrees very well with the resonance angular velocity of internal gravity wave car, estimated by the theoretical equation proposed by Thorpe, as observed for α=1. However α_m has two local maxima for larger Ra, which is peculiar to the case of larger a. The time variation of components of fluctuating midplane Nusselt number shows that the phase at the maximum value of α_m agrees well with that of the fluctuating component of velocity for the first resonance angular velocity ω_r. For the other angular velocity ω_<r2> the phase of α_m agrees with that of the fluctuating component of temperature. Moreover, we found that the boundary angular velocity ω_0 between the first two ω regions among five regions, which classify the thermal convection fields against ω, can be expressed by a function of α, Ra and Pr and that α_m is independent of α and Ra for relatively wide range of ω/ω_0.
2006-07-25