Ultimate regime of Rayleigh-Benard turbulence: Sub-regimes and their scaling relations for Nu vs. Ra and Pr
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| Format: | Preprint |
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2024
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| _version_ | 1866914883018162176 |
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| author | Shishkina, Olga Lohse, Detlef |
| author_facet | Shishkina, Olga Lohse, Detlef |
| contents | We offer a new model for the heat transfer and the turbulence intensity in strongly driven Rayleigh-Benard turbulence (the so-called ultimate regime), which in contrast to hitherto models is consistent with the new mathematically exact heat transfer upper bound of Choffrut et al. [J. Differential Equations 260, 3860 (2016)] and thus enables extrapolations of the heat transfer to geo- and astrophysical flows. The model distinguishes between four subregimes of the ultimate regime and well describes the measured heat transfer in various large-Ra experiments. In this new representation, which properly accounts for the Prandtl number dependence, the onset to the ultimate regime is seen in all available large-Ra data sets, though at different Rayleigh numbers, as to be expected for a non-normal-nonlinear instability. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2407_16573 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Ultimate regime of Rayleigh-Benard turbulence: Sub-regimes and their scaling relations for Nu vs. Ra and Pr Shishkina, Olga Lohse, Detlef Fluid Dynamics We offer a new model for the heat transfer and the turbulence intensity in strongly driven Rayleigh-Benard turbulence (the so-called ultimate regime), which in contrast to hitherto models is consistent with the new mathematically exact heat transfer upper bound of Choffrut et al. [J. Differential Equations 260, 3860 (2016)] and thus enables extrapolations of the heat transfer to geo- and astrophysical flows. The model distinguishes between four subregimes of the ultimate regime and well describes the measured heat transfer in various large-Ra experiments. In this new representation, which properly accounts for the Prandtl number dependence, the onset to the ultimate regime is seen in all available large-Ra data sets, though at different Rayleigh numbers, as to be expected for a non-normal-nonlinear instability. |
| title | Ultimate regime of Rayleigh-Benard turbulence: Sub-regimes and their scaling relations for Nu vs. Ra and Pr |
| topic | Fluid Dynamics |
| url | https://arxiv.org/abs/2407.16573 |