Internal Gravity Wave Resonance of Thermal Convection Fields in Rectangular Cavities with Heat-Flux Vibration (Effects of Aspect Ratio on the Fields)

摘要

In this paper the thermal convection field and its resonance phenomena in a rectangular cavity with heat-flux vibration are numerically examined and the results are compared with those of a square cavity. As in the case of α = 1, the critical angular velocity at which the relative amplitude of the midplane Nusselt number α_m has a local maximum agrees very well with the resonance angular velocity of the internal gravity wave ω_r, estimated by the theoretical equation proposed by Thorpe, even when the aspect ratio is α = 5 and the Prandtl number is Pr = 0.71 for a range of the Rayleigh number Ra. However, α_m has two local maxima for a larger Ra, which is peculiar to the case of larger α. The time variation of sub-components of the fluctuating component of the midplane Nusselt number shows that the phase at the maximum value of α_m agrees well with that of the sub-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 sub-component of temperature. Moreover, we found that the boundary angular velocity ω_0 between the first two of the five ω 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 a relatively wide range of ω/ω_0.