Temperature power spectra and the viscous boundary layer in thermal turbulence: the role of Prandtl number
نویسندگان
چکیده
We report an experimental investigation on the relationship between the thickness of the viscous boundary layer and the highest excitation (or cuto ) frequency of the temperature power spectrum in turbulent convection, using water as working uid. For the range of the Rayleigh number spanned in the experiment (10–10), we con rm that the peak position in the cuto frequency pro le can be used as an alternative measure of the viscous boundary layer thickness [A. Belmonte et al. Phys. Rev. Lett. 70 (1993) 4067]. But a previous justi cation given for this method is not borne out in our system. The implications of the current work will be discussed with respect to results from other experiments using uids with Prandtl numbers di erent than that of water. c © 2000 Elsevier Science B.V. All rights reserved. PACS: 47.27.-i; 47.27.Te; 44.25.+f
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