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Wilczek, Michael ; Xu, Haitao ; Narita, Yasuhito:
A note on Taylor's hypothesis under large-scale flow variation.
In: Nonlinear Processes in Geophysics.
Bd. 21
(2014)
Heft 3
.
- S. 645-649.
ISSN 1607-7946
DOI: https://doi.org/10.5194/npg-21-645-2014
Abstract
Experimental investigations of turbulent velocity fields often invoke Taylor's hypothesis (also known as frozen turbulence approximation) to evaluate the spatial structure based on time-resolved single-point measurements. A crucial condition for the validity of this approximation is that the turbulent fluctuations are small compared to the mean velocity, in other words, that the turbulence intensity must be low. While turbulence intensity is a well-controlled parameter in laboratory flows, this is not the case in many geo- and astrophysical settings. Here we explore the validity of Taylor's hypothesis based on a simple model for the wavenumber-frequency spectrum that has recently been introduced as a generalization of Kraichnan's random sweeping hypothesis. In this model, the fluctuating velocity is decomposed into a large-scale random sweeping velocity and small-scale fluctuations, which allows for a precise quantification of the influence of large-scale flow variations. For turbulence with a power-law energy spectrum, we find that the wavenumber spectrum estimated by Taylor's hypothesis exhibits the same power-law as the true spectrum, yet the spectral energy is overestimated due to the large-scale flow variation. The magnitude of this effect, and specifically its impact on the experimental determination of the Kolmogorov constant, are estimated for typical turbulence intensities of laboratory and geophysical flows.
Weitere Angaben
| Publikationsform: | Artikel in einer Zeitschrift |
|---|---|
| Begutachteter Beitrag: | Ja |
| Institutionen der Universität: | Fakultäten > Fakultät für Mathematik, Physik und Informatik > Physikalisches Institut > Lehrstuhl Theoretische Physik I > Lehrstuhl für Theoretische Physik I - Univ.-Prof. Dr. Michael Wilczek Profilfelder > Advanced Fields > Nichtlineare Dynamik Fakultäten Fakultäten > Fakultät für Mathematik, Physik und Informatik Fakultäten > Fakultät für Mathematik, Physik und Informatik > Physikalisches Institut Fakultäten > Fakultät für Mathematik, Physik und Informatik > Physikalisches Institut > Lehrstuhl Theoretische Physik I Profilfelder Profilfelder > Advanced Fields |
| Titel an der UBT entstanden: | Nein |
| Themengebiete aus DDC: | 500 Naturwissenschaften und Mathematik > 530 Physik |
| Eingestellt am: | 23 Feb 2022 08:22 |
| Letzte Änderung: | 24 Feb 2022 11:34 |
| URI: | https://eref.uni-bayreuth.de/id/eprint/67564 |