Characteristics of space-time energy spectra in turbulent channel flows
| Autor: | Chunxiao Xu, Chenhui Geng, Ting Wu, Yichen Yao, Guowei He |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Fluid Flow and Transfer Processes
Physics Turbulence Computational Mechanics Phase (waves) 01 natural sciences Spectral line Standard deviation 010305 fluids & plasmas Computational physics Amplitude Modeling and Simulation 0103 physical sciences Wavenumber 010306 general physics Energy (signal processing) Doppler broadening |
| Zdroj: | Physical Review Fluids. 2 |
| ISSN: | 2469-990X |
| DOI: | 10.1103/physrevfluids.2.084609 |
| Popis: | An energy spectrum is preliminarily characterized by its mean and standard deviation. In this study, we derive exact expressions for the means and bandwidths of space-time energy spectra at fixed frequencies. The mean wave numbers are used to determine the phase velocities that bridge from temporal spectra to space-time spectra. The bandwidths are used to measure the well-known spectral broadening. We show that phase velocities alone are insufficient to determine the bandwidths of energy spectra. As a result, the cross-spectral method predicts narrower bandwidths of energy spectra. Therefore, in addition to phase velocities, amplitudes are used to rescale the space-time energy spectra, leading to the correct bandwidths. Existing data from direct numerical simulations of turbulent channel flows validate the rescaling approach. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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