25,593 research outputs found

    Kolmogorov and scalar spectral regimes in numerical turbulence

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    Velocity and passive-scalar spectra for turbulent fields generated by a forced three-dimensional simulation and Taylormicroscale Reynolds numbers up to 83 are shown to have distinct spectral regimes, including a Kolmogorov inertial subrange. Both one- and three-dimensional spectra are shown for comparison with experiment and theory, respectively. When normalized by the Kolmogorov dissipation scales velocity spectra collapse to a single curve and a high-wavenumber bulge is seen. The bulge leads to an artificially high Kolmogorov constant, but is consistent with recent measurements of the velocity spectrum in the dissipation regime and the velocity-derivative skewness. Scalar spectra, when normalized by the Oboukov-Corrsin scales, collapse to curves which depend only on Prandtl number and show a universal inertial-convective subrange, independent of Prandtl number. When normalized by the Batchelor scales, the scalar spectra show a universal dissipation regime which is independent of Prandtl numbers from 0.1 to 1.0. The time development of velocity spectra is illustrated by energy-transfer spectra in which distinct pulses propagate to high wavenumbers

    A farewell to Neo-Punic: Tac-Caghqi revisited

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    The alleged inscriptions in the south-east hypogeum of Tac-Caghqi (within the premises of St Nicholas College in Rabat, Malta) were discussed in depth by Mons. Benedetto Rocco in 1972. Rocco interpreted the glyphs as Neo-Punic, with a long 'Inscription' supposedly consisting of a prayer to appease the deceased through the offering of a gift, and an alleged minor 'Inscription' addressing the dead to 'rise'. These readings were discussed against the notion of possible libation rites that may have been a custom within the hypogeum, as suggested by the tomb furniture in situ. Rocco based his readings of the script and types of letters on his previous study of further alleged Punic and Neo-Punic inscriptions within cave sites in Palermo and Favignana (Sicily), in combination with semantic analysis of Biblical Hebrew. Nevertheless, the supposed Tac-Caghqi inscriptions come across as ambiguous sets of glyphs that are illegible, and actually cannot be deemed Punic or Neo-Punic script.peer-reviewe
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