CONSERVATIVE CASCADE OF KINETIC ENERGY IN COMPRESSIBLE TURBULENCE
- Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
The physical nature of compressible turbulence is of fundamental importance in a variety of astrophysical settings. We investigate the question: 'At what scales does the mechanism of pressure-dilatation operate?' and present the first direct evidence that mean kinetic energy cascades conservatively beyond a transitional 'conversion' scale range despite not being an invariant of the dynamics. We use high-resolution 1024{sup 3} subsonic and transonic simulations. The key quantity we measure is the pressure-dilatation cospectrum, E{sup PD}(k), where we show that it decays at a rate faster than k{sup -1} in wavenumber in at least the subsonic and transonic regimes. This is sufficient to imply that mean pressure-dilatation acts primarily at large scales and that kinetic and internal energy budgets statistically decouple beyond a transitional scale range. However, we observe that small-scale dynamics remains highly compressible locally in space and that the statistical decoupling in the energy budgets is unrelated to the existence of a subsonic scale range. Our results suggest that an extension of Kolmogorov's inertial-range theory to compressible turbulence is possible.
- OSTI ID:
- 22047788
- Journal Information:
- Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 751; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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