Taylor’s hypothesis and two-point coherence measurements |
| |
| Authors: | Chenning Tong |
| |
| Institution: | (1) Department of Meteorology, Pennsylvania State University, 16082 University Park, PA, USA |
| |
| Abstract: | Experimentally obtained time coherence has traditionally been interpreted as streamwise one-dimensional spatial coherence
through Taylor’s hypothesis. We calculate corrections to the highwavenumber part of the coherence to account for the errors
caused by the deviation from Taylor’s hypothesis in high-intensity turbulent flows. The small-scale turbulence is assumed
to be frozen and convected by a fluctuating convection velocity. Both Lumley’s two-term approximation and the Gaussian approximation
are used in the calculations. In general, we find that the coherence for crossstream separations is significantly overestimated
by the direct use of Taylor’s hypothesis, the error increasing with wavenumber; that for streamwise separations is underestimated.
The analyses are compared with cross-stream coherence measurements in the atmospheric surface layer. Our results indicate
that predictions from Lumley’s approximation yield better agreement with experimental data for cross-stream separations than
those from the Gaussian model. Our study suggests that reliable measurement of two-point spatial coherence can be achieved
only for scales not too small compared to the sensor separation. |
| |
| Keywords: | Turbulence Coherence Taylor’ s hypothesis Surface layer |
| 本文献已被 SpringerLink 等数据库收录！ |
|
