The Rayleigh-Benard Instability and the Evolution of Turbulence

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In this paper were view the experimental progress that has been made in the srudy of the evolution of turbulence in low Prandtl number fluids confined by cylindrical containers and heated from below. Heat transport measurements have revealed that the evolution and nature of non-periodic (i.e., turbulent)states depend upon the aspect ratio Γ. For large Γ, the fluid flow is non-periodeic for Rayleigh numbers R-^^>R_t, with R_t at most a few percent larger than the critical Rayleigh number R_c for the Rayleigh-Benard instability. Inthar case the mean amplitude of the non-periodic contribution extrapolates to zero at R_c. For R>R_t, the power is centered about zero frequency. For intermediate aspect ratios(Γcong 5),R_t cong 2R_c and at R_t the non-periodically time dependent state has a non-zero amplitude. In this case there is also evidence for the oscillatory instabikity (OI) of Clever and Busse when R>R_p; but R_p>R_t and the spectral features associated with the OI are broadened. For small aspect ratios (Γcong 2),R_t is increased dramatically,and a quasi-harmonic state evolves for R_p<R<R_t. Above R_t the power of the non-periodic state is concentrated near finite frequencies.
理論物理学刊行会の論文
1979-04-01